The Trump administration has revived an investigation into email records from Hillary Clinton's former aides, The Washington Post reported Saturday.
Investigators reportedly reached out to roughly 130 officials in recent weeks over years-old emails, and told them the emails were retroactively classified and are now considered potential security violations.
The investigation began roughly 18 months ago, but the officials told The Post that investigators appeared to drop the effort but picked it up again last month.
State Department investigators in recent weeks have been contacting former Hillary Clinton aides over their email records, The Washington Post reported Saturday evening.
Investigators have reached out to roughly 130 officials in recent weeks over years-old emails and told them the emails were retroactively classified and are now considered potential security violations, The Post reported, citing current and former State Department officials and letters they received.
Related: Hillary Clinton through the years
Hillary Clinton through the years
Hillary Clinton through the years
A 1992 photo shows then Governor of Arkansas Bill Clinton (L) and his wife Hillary (R) embracing. (Photo credit AFP/Getty Images)
Democratic presidential candidate Bill Clinton (L) waves to supporters as he holds the hand of his wife Hillary, 22 July, 1992 after speaking at a rally. St. Louis was the last stop on the Clinton-Gore campaign's bus tour. The crowd was estimated at 40,000. (Photo credit Tim Clary, AFP/Getty Images)
US President Bill Clinton's wife Hillary Rodham Clinton (l) in a picture taken 16 January 1993 in Little Rock, hugs her daughter Chelsea during a farewell address to the people of Arkansas at an airport rally. The Clinton family then left for Charlottesville, Virginia for the start of the planned bus trip to Washington, DC. (Photo credit J. David Ake, AFP/Getty Images)
First Lady Hillary Clinton (R) watches over as 12-year-old Chevon Perry (L) works on a lesson at P.S. 115 Elementary School 26 January 1993. Clinton made her first trip as first lady to New York to receive an award for her service to children. (Photo credit Tim Clary, AFP/Getty Images)
First Lady Hillary Clinton responds to applause, 12 February 1993, in Arlington, VA, as U.S. President Bill Clinton stands behind her. (Photo credit Robert Giroux, AFP/Getty Images)
U.S. First Lady Hillary Rodham Clinton laughs as she is presented a bouquet of flowers by Japanee children 08 July 1993 at the Meguro waste incineration plant in Tokyo, Japan. Mrs. Clinton, maintaining a high profile during the G7 summit, is popular in Japan. (Photo credit David Nelson, AFP/Getty Images)
U.S. President Bill Clinton (R) and First Lady Hillary Rodham Clinton (L) listen to Karl Kregor explain, 16 September 1993 in Washington, D.C. why he is afraid of losng health isurance for his family.The Clintons met at the White House with citizens who shared problems they have had with the present health care system. Clinton is scheduled to present his health care plan to a joint session of congress 22 September. (Photo credit Paul Richards, AFP/Getty Images)
U.S. First Lady Hillary Clinton responds 22 September 1993 to applause from a joint session of the U.S. Congress in Washington, D.C. after President Bill Clinton saluted her as the 'talented navigator' for the national health plan he is proposing. Standing alongside the first lady is Dr. T. Berry Brazelton (L), a noted pediatrician and author. (Photo credit J. David Ake, AFP/Getty Images)
First Lady Hillary Clinton attends the Winter Olympics in Lillehammer, Norway. (Photo by Clive Brunskill, Getty Images)
US First Lady Hillary Clinton (L) and Wife of French Prime Minister Edouard Balladur, Marie-Josephe Balladur pose at the Hotel Matignon on June 7, 1994. (Photo credit Pascal Pavani, AFP/Getty Images)
First Lady Hillary Rodham Clinton (C) smiles at a friend in the crowd 28 September 1994 as she stands next to Russian First Lady Naina Yeltsin (L) during a ceremony at the Library of Congress. Mrs. Yeltsin was accompanying her husband on his visit to Washington for a summit meeting with US President Bill Clinton. AFP YEARENDER (Photo credit Joshua Roberts, AFP/Getty Images)
US President Bill Clinton (R) and First Lady Hillary Clinton leave the White House for the presidential retreat at Camp David, Maryland, 13 Janaury. President Clinton is waving a copy of the morning pool report on his activities, which was written as a poem. The poem begins ' The president jogged at Fort McNair....of him we saw not hide nor hair,' and ends with the slogan 'Burma Shave.' (Photo credit Paul Richards, AFP/Getty Images)
US First Lady Hillary Clinton laughs as she listens to political humorist Bill Maher address the annual dinner of the Radio and Television Correspondents Association in Washington on March 14, 1995. (Photo credit Paul J. Richards, AFP/Getty Images)
US First Lady Hillary Clinton (L) poses with 'Robo Crook'(R) a character from the television program Sesame Street at the White House in Washington, DC 26 June. Mrs. Clinton moderated a panel discussion on the role of Public Television in educating children. (Photo credit Jamal Wilson, AFP/Getty Images)
Hillary Clinton, wife of US President Bill Clinton, talks with Britain's Queen Elizabeth 30 November in the Grand Entrance Hall of Buckingham Palace in London. President Clinton and Hillary Clinton arrived 29 November morning for a three-day visit which will be dominated by the Northern Ireland peace process. (Photo credit John Stillwell, AFP/Getty Images)
US First Lady Hillary Clinton greets guests after speaking at the Women's Leadership Forum at the World Trade Center 20 June in Boston, Massachusetts.The First Lady will be in Washington DC later 20 June for the arrival of the Olympic Torch at the White House. (Photo credit John Mottern, AFP/Getty Images)
US First Lady Hillary Rodham Clinton waves from the bullet-proof presidential limousine as she and US President Bill Clinton leave Sydney International Airport on November 19, 1996. The Clintons arrived in Australia from Hawaii at the start of a five-day working and holiday visit. A(Photo credit should read Torsten Blackwood, AFP/Getty Images)
US President Bill Clinton (L)and his wife Hillary listen to speakers at a coalition for America's Children event at the White House in Washington, on March 3, 1997. The Clintons will begin a series of television, radio and newspaper public service annoucements, urging Americans to help improve the lives of children. (Photo credit Joyce Naltchayan, AFP/Getty Images)
Hillary Clinton proudly shows the tea-pot which had been a gift from community worker Joyce McCartan on the Clintons' previous visit to Belfast, during her speech at the University of Ulster, in Belfast 31 October. The memorial speech, named after Joyce McCartan, who died last year, called on parties from both sides to make compromises for peace in the country. The American First Lady is on a whistle-stop tour visiting Dublin, Belfast and London in three days. (Photo credit Alan Lewis, AFP/Getty Images)
US First Lady Hillary Clinton talks with NBC TV anchorwoman Katie Couric (L)10 September during an event in the East Room of the White House promoting colon cancer awareness and prevention. Hillary Clinton announced a new research grant to fight colon cancer and unveiled a new public service announcement to promote prevention. (Photo credit Tim Sloan, AFP/Getty Images)
US President Bill Clinton, First Lady Hillary Clinton, and their daughter Chelsea tour the Forbidden City in Beijing, as a Chinese security agent (rear) looks on 28 June during their 9 day official trip to China. The three later toured the Great Wall. (Photo credit Paul J. Richards, AFP/Getty Images)
US First Lady Hillary Rodham Clinton listens to speakers during ceremonies 11 January to unveil the new Dolley Madison commemorative silver dollar coin at the White House in Washington, DC. The coin, designed by Tiffany and Company is available at the US Mint and celebrates the life, achievements and 150th anniversary of Dolley Madison's death. (Photo credit Tim Sloan, AFP/Getty Images)
First Lady Hillary Clinton works the crowd as she arrives at Prior Aviation Services in Buffalo, New York, 07 February, 2000. Mrs. Clinton, who officially announced her run for US Senate 06 February, 2000, made Buffalo her fisrt campaign stop. ((Photo credit Don Emmert, AFP/Getty Images)
US First Lady Hillary Rodham Clinton (R) announces the formation of the Millenium Trails Celebration Committee 19 April, 1999 at the Central Park Boathouse in New York, New York. Millenium Trails is a national initiative to create and enhance hiking, cultural and other trails across the country. It partners the White House Millenium Council, the Department of Transportation and the Rails-to-Trails Conservancy. (Photo credit Stan Honda, AFP/Getty Images)
US President Bill Clinton (L) and First Lady Hillary Rodham Clinton (R) wait on the South Portico for the arrival of King Juan Carlos I and Queen Sofia 23 February 2000 at the White House in Washington, DC. The Clintons hosted an arrival ceremony for their visit. (Photo credit Stephen Jaffe, AFP/Getty Images)
US First Lady and New York US Senate candidate Hillary Clinton waves to the crowd as she arrives on the stage at the Democratic National Convention 14 August 2000 at the Staples Center in Los Angeles, California. (Photo credit Paul J. Richards, AFP/Getty Images)
U.S. Senate candidate and First Lady Hillary Rodham Clinton gives a thumbs-up sign to supporters at the Hispanic Day Parade October 8, 2000 in New York City. (Photo by Chris Hondros/Newsmakers via Getty)
US First Lady Hillary Clinton smiles during a press conference in New York 08 November, 2000. Clinton defeated Congressman Rick Lazio to win the US Senate seat for New York being vacated by Patrick Moynihan. AFP PHOTO Doug KANTER (Photo credit Doug Kanter, AFP/Getty Images)
U.S. Senator-elect, First Lady Hillary Clinton walks through the U.S. Capitol during an orientation day for new senators December 5, 2000 in Washington, DC. (Photo by Mark Wilson/Newsmakers via Getty)
Senator Hillary Rodham Clinton listens during Labor Secretary-designate Elaine Chao's confirmation hearing January 24, 2001 on Capitol Hill in Washington, DC. (Photo by Alex Wong/Newsmakers via Getty)
Sen. Hillary Rodham Clinton (D-NY) attends a press conference to address the equal pay act June 12, 2001 Capitol Hill in Washington, DC. The AFL-CIO''s Working Women Working Together held a news conference to introduce a campaign for legislation to step up enforcement of the 1963 Equal Pay Act. (Photo by Alex Wong/Getty Images)
New York Senator and former First Lady, Hillary Rodham Clinton, signs copies of her autobiography, 'Living History' at Waterstone?s bookstore on July 3, 2003 in London, England. In her autobiography, Clinton reveals her presidential ambitions and her thoughts on Monica Lewinsky. (Photo by Scott Barbour/Getty Images)
Senator Hillary Rodham Clinton appears with Jon Stewart during 'The Daily Show With Jon Stewart' at the Daily Show Studios October 8, 2003 in New York City. (Photo by Scott Gries/Getty Images for The Daily Show)
Sen. Hillary Rodham Clinton (D-NY) attends a news conference in front of the United Nations to denounce the International Court of Justice's recent decision on Israel's security fence July 9, 2004 in New York City. The International Court in The Hague has ruled that the barrier Israel has nearly completed in the West Bank violates international law, and the court ruled that the United Nations should take action to stop its construction. (Photo by Spencer Platt/Getty Images)
U.S. Senator Hillary Rodham Clinton (D-NY) speaks while former U.S. President Bill Clinton listens during a visit to the New York Buddhist Vihara December 31, 2004 in the Queens borough of New York City. The Clintons toured the temple where volunteers have been collecting donations for victims of the tsunami in Sri Lanka. (Photo by Stephen Chernin/Getty Images)
Sen. Hillary Rodham Clinton (D-NY) speaks at a Democratic forum on Social Security reform at Pace University March 4, 2005 in New York City. A group of Democratic Senators spoke at the forum to protest U.S. President George W. Bush's plan to privatize Social Security. (Photo by Mario Tama/Getty Images)
U.S. Senator Hillary Clinton (D-NY) stands near her portrait during an unveiling ceremony at the Smithsonian April 24, 2006 in Washington DC. President Clinton's portrait will hang in the National Portrait Gallery's 'America's President's' exhibit. (Photo by Mark Wilson/Getty Images)
Hillary Rodham Clinton watches a speaker on the final day of the Clinton Global Initiative annual meeting September 22, 2006 in New York City. A large array of notables in the worlds of politics, human rights, and philanthropy have gathered in the New York for three days of seminars and pledges on global issues. (Photo by Chris Hondros/Getty Images)
Democratic presidential hopeful Sen. Hillary Clinton (D-NY) speaks during a post primary rally at Southern New Hampshire University January 8, 2007 in Manchester, New Hampshire. After losing to Sen. Barack Obama (D-IL) and Edwards in Iowa, Clinton (D-NY) won New Hampshire, the first of the nation's presidential primaries. (Photo by Chris Hondros/Getty Images)
US Senator Hillary Clinton and daughter Chelsea are seen at the lectern during a soundcheck at the Democratic National Convention 2008 at the Pepsi Center in Denver, Colorado, on August 26, 2008. Clinton takes the stage tonight vowing to unite Democrats after her primary battle with Barack Obama, on the second day of the convention that will crown him as White House nominee. The DNC is held 25-28 August. (Photo credit Stan Honda, AFP/Getty Images)
Democratic presidential nominee U.S. Sen. Barack Obama (D-IL) and Sen. Hillary Clinton (D-NY) attend a campaign rally together at Amway Arena October 20, 2008 in Orlando, Florida. Obama continues to campaign against his challenger, Republican presidential nominee Sen. John McCain (R-AZ) while Election Day begins to draw near. (Photo by Joe Raedle/Getty Images)
Former US President Bill Clinton (L) and US Secretary of State-designate Hillary Clinton (R) attend the inauguration of US President Barack Obama at the US Capitol in Washington, DC, on January 20, 2009. (Photo credit Robyn Beck, AFP/Getty Images)
U.S. Secretary of State Hillary Clinton (L) is sworn in as her husband former President Bill Clinton (2nd L), and her daughter Chelsea (R) look on during a ceremonial swearing-in at the State Department February 2, 2009 in Washington, DC. Clinton is the 67th Secretary of State of the United States of America. (Photo by Alex Wong/Getty Images)
US Secretary of State Hillary Clinton attends a press conference on February 21, 2009 in Beijing, China. Clinton is on a three day visit to the Chinese capital, as part of her first diplomatic tour to Asia. (Photo by Guang Niu/Pool/Getty Images)
US Secretary of State Hillary Clinton speaks on the US vision for Asia-Pacific multilateral engagement at the East-West Center in Honolulu January 12, 2010. (Photo credit Mandel Ngan, AFP/Getty Images)
US Secretary of State Hillary Clinton, smiles during a press conference after Middle East Quartet talks in Moscow on March 19, 2010. The International Quartet on the Middle East urged Israel to freeze all settlement activity and expressed deep concern about the situation in Gaza, UN Secretary General Ban Ki-moon said. (Photo credit Yuri Kadobnov, AFP/Getty Images)
US Secretary of State Hillary Clinton speaks before signing the US-China Consultation on People-to-People Exchange agreement at the National Center for the Performing Arts in Beijing on May 25, 2010. The United States and China were wrapping up strategic talks aimed at smoothing out differences on currency and trade issues, as Washington presses Beijing to get tough on North Korea. (Photo credit Saul Loeb, AFP/Getty Images)
U.S. Secretary of State Hillary Clinton listens to Ambassador-Designate to Russia Michael McFaul during his swearing-in ceremony at the State Department January 10, 2011 in Washington, DC. McFaul is President Barack Obama's top adviser on Russia and has been involved in the reset of relations between the two countries and the signing of the New START treaty. (Photo by Astrid Riecken/Getty Images)
U.S. Secretary of State Hillary Clinton speaks during the South Sudan International Engagement Conference December 14, 2011 at the Marriott Wardman Park Hotel in Washington, DC. The two-day conference was to highlight the national development vision of South Sudan and the opportunities for investment in the country. (Photo by Alex Wong/Getty Images)
US Secretary Hillary Clinton speaks to reporters during a joint press conference with Qatar's Prime Minister and Foreign Minister Hamad bin Jassim bin Jabr Al-Thani at the Department of State January 11, 2012 in Washington, DC. (Photo credit Karen Bleier, AFP/Getty Images)
US Secretary of State Hillary Clinton (R) shakes hands with Moroccan Foreign Minister Saad-Eddine el-Othmani prior to meetings at the State Department in Washington, DC, on March 15, 2012. (Photo credit Saul Loeb, AFP/Getty Images)
US Secretary of State Hillary Clinton smiles during a joint press conference with Australian Foreign Minister arr following their meeting at the State Department in Washington, DC, on April 24, 2012. (Photo credit Jewel Samad, AFP/Getty Images)
U.S. Secretary of State Hillary Clinton testifies before the House Foreign Affairs Committee on Capitol Hill January 23, 2013 in Washington, DC. Lawmakers questioned Clinton about the security failures during the September 11 attacks against the U.S. mission in Benghazi, Libya, that led to the death of four Americans, including U.S. Ambassador Christopher Stevens. (Photo by Chip Somodevilla/Getty Images)
Former US Secretary of State Hillary Clinton addresses the Vital Voices Global Awards ceremony at the Kennedy Center in Washington on April 2, 2013. The event honors 'women leaders from around the world who are the unsung heroines to strengthen democracy, increase economic opportunity, and protect human rights,' according to the group's website. (Photo credit Nicholas Kamm, AFP/Getty Images)
Former US Secretary of State Hillary Clinton speaks about the situation in Syria after meeting with US President Barack Obama, prior to remarks about US efforts to combat wildlife trafficking at a White House forum at the Eisenhower Executive Office Building in Washington, DC on September 9, 2013. (Photo credit Saul Loeb, AFP/Getty Images)
Former Secretary of State Hillary Rodham Clinton speaks on stage at the Pennsylvania Conference For Women 2013 at Philadelphia Convention Center on November 1, 2013 in Philadelphia, Pennsylvania. (Photo by Lisa Lake/Getty Images for Pennsylvania Conference for Women)
Hillary Clinton attends the New-York Historical Society 2014 History Makers Gala at Mandarin Oriental Hotel on November 21, 2014 in New York City. (Photo by Brad Barket/Getty Images)
Hillary Rodham Clinton Book Signing For 'Hard Choices' at Barnes & Noble bookstore at The Grove on June 19, 2014 in Los Angeles, California. (Photo by Frazer Harrison/Getty Images)
Former U.S. Secretary of State Hillary Clinton delivers a keynote address during the Watermark Silicon Valley Conference for Women on February 24, 2015 in Santa Clara, California. Former Secretary of State Hillary Clinton delivered a keynote address to thousands of women in attendance for the Watermark Silicon Valley Conference for Women. (Photo by Justin Sullivan/Getty Images)
Former Secretary of State Hillary Clinton speaks on stage during a ceremony to induct her into the Irish America Hall of Fame on March 16, 2015 in New York City. The Irish America Hall of Fame was founded in 2010 and recognizes exceptional figures in the Irish American community. (Photo by Yana Paskova/Getty Images)
Former U.S. Secretary of State, Hillary Clinton, gives the Honorary Degree Recipient Address after receiving an Honorary Doctorate of Law at Swansea University, in Swansea, Britain October 14, 2017. REUTERS/Mary Turner
Former U.S. Secretary of State, Hillary Clinton speaks during an interview with Mariella Frostrup at the Cheltenham Literature Festival in Cheltenham, Britain October 15, 2017. REUTERS/Rebecca Naden
Former U.S. Secretary of State Hillary Clinton smiles and winks at someone she recognizes as she takes the stage to discuss her new book ?What Happened? as she launches a 15-city book tour at the Warner Theatre in Washington, U.S. September 18, 2017. REUTERS/Jonathan Ernst TPX IMAGES OF THE DAY
Former Secretary of State Hillary Clinton signs a copy of her new book 'What happened' at Barnes & Noble bookstore at Union Square in Manhattan, New York City, U.S., September 12, 2017. REUTERS/Andrew Kelly
Hillary Clinton with host Graham Norton during filming of The Graham Norton Show at the London Studios, to be aired on BBC One on Friday evening. (Photo by Ian West/PA Images via Getty Images)
TORONTO, ON- SEPTEMBER 28 - Hillary Clinton visits Toronto and delivers a speech at the Enercare Centre while on the book tour for her book 'What Happened' at the in Toronto. September 28, 2017. (Steve Russell/Toronto Star via Getty Images)
NEW YORK, NY - JUNE 07: Hillary Rodham Clinton speaks at the 2017 Stephan Weiss Apple Awards on June 7, 2017 in New York City. (Photo by Monica Schipper/Getty Images for Urban Zen Foundation)
NEW YORK, NY - JUNE 01: Former US Secretary of State Hillary Rodham Clinton speaks during BookExpo 2017 at the Jacob K. Javits Convention Center on June 1, 2017 in New York City. (Photo by John Lamparski/WireImage)
NEW YORK, NY - MAY 03: Former US Secretary of State and WOV Honoree Hillary Clinton speaks onstage at the Ms. Foundation for Women 2017 Gloria Awards Gala & After Party at Capitale on May 3, 2017 in New York City. (Photo by Monica Schipper/Getty Images for The Foundation for Women)
Former US Secretary of State Hillary Clinton speaks at the Eighth Annual Women in the World Summit at Lincoln Center for the Performing Arts on April 6, 2017, in New York City. / AFP PHOTO / ANGELA WEISS (Photo credit should read ANGELA WEISS/AFP/Getty Images)
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The officials received letters in August saying, "You have been identified as possibly bearing some culpability" in "security incidents," according to The Post.
The investigation began roughly 18 months ago, but the officials told The Post that investigators appeared to drop the effort but picked it up again last month.
The Post cited two senior State Department official who said the probe was not politically motivated, and one said that it took roughly three-and-a-half years to go through "millions of emails."
The timing of the revived investigation is already being scrutinized — President Donald Trump has recently become the subject of House Democrats' impeachment inquiry after revelations that he pressed the Ukrainian president to investigate one of his top political rivals.
The Post cited one former senior US official familiar with the State Department's investigation who said the renewed push targeting former Clinton aides was a way for Republicans to "keep the Clinton email issue alive" and "tarnish a whole bunch of Democratic foreign policy people."
Clinton's use of a private email server when she was Secretary of State unleashed a years-long controversy that rattled her 2016 presidential bid and fueled calls from Trump and many Republicans for criminal prosecution.
Clinton was previously investigated by the State Department, as well as the FBI and Congress. Though former FBI Director James Comey infamously accused Clinton of being "extremely careless" in her handling of classified information, she was never criminally charged.