Idrees Ali, Warren Strobel, Grant McCool and Andrew Hay
Aug 25th 2016 6:33AM
WASHINGTON, Aug 24 (Reuters) - Four of Iran's Islamic Revolutionary Guard Corps (IRGC) vessels "harassed" a U.S. warship on Tuesday near the Strait of Hormuz, a U.S. defense official said, amid Washington's concerns about Iran's posture in the Gulf and in the Syrian civil war.
The official, speaking on the condition of anonymity, said on Wednesday that two of the Iranian vessels came within 300 yards of the USS Nitze in an incident that was "unsafe and unprofessional."
The vessels harassed the destroyer by "conducting a high speed intercept and closing within a short distance of Nitze, despite repeated warnings," the official said.
IRGC, the Islamic Republic's praetorian guard, is suspicious of U.S. military activity near Iran's borders and appears to be sticking to a familiar posture in the Gulf that predates last year's nuclear accord between Iran and six world powers, including the United States.
The United States and other countries are concerned about Iran's support for Syrian President Bashar al-Assad, its ballistic missile program, and its backing for Shiite militias that have abused civilians in Iraq.
The U.S. defense official said that in Tuesday's incident the USS Nitze tried to communicate with the Iranian vessels 12 times, but received no response. It also fired 10 flares in the direction of two of the Iranian vessels.
"The Iranian high rate of closure... created a dangerous, harassing situation that could have led to further escalation, including additional defensive measures by Nitze," the official said.
RELATED: See how US and Iranian relations have changed through time
United States and Iran Relations throughout time
United States and Iran Relations throughout time
Two lines of troops loyal to Ayatollah Ruhollah Khomeini stand in front of the U.S. Embassy during shooting in the compound, Feb. 15, 1979 in Tehran. (AP Photo)
In this Nov. 9, 1979, file photo, one of the hostages being held at the U.S. Embassy in Tehran is displayed blindfolded and with his hands bound to the crowd outside the embassy. The U.S. and Iran cut off diplomatic ties in 1979 after the Islamic Revolution and the storming of the U.S. Embassy in Tehran, where 52 Americans were held hostage for more than a year. Since his inauguration in 2009, President Barack Obama has expressed a willingness to meet with the Iranians without conditions. The U.S. and Iran secretly engaged in high-level, face-to-face talks, at least three times over the past year, in a high stakes diplomatic gamble by the administration that paved the way for the historic deal aimed at slowing Iran's nuclear program. (AP Photo/File)
President Carter faces reporters at the White House as he announces the U.S. will seek economic sanctions against Iran, Dec. 21, 1979 in Washington. Secretary of State cyrus Vance looks on. Vance died Saturday, Jan. 12, 2002. He was 84. Appointed secretary of state by Jimmy Carter in 1977, Vance promoted reconciliation with Russia, human rights as a pillar of American foreign policy, normalization of relations with China and, above all, diplomacy as the alternative to using force. (AP Photo)
This is the entrance to the U.S. Embassy in Tehran, Iran where 63 people are being held hostage, seen in 1980. Graffiti on the wall at left reads: "Dear American minority, brothers and sisters (Blacks and Indians) study the holy Koran and start a revolution against U.S. discrimination. God and Iranian Muslim people are supporting you. Down with Reagan." (AP Photo)
Return of the hostages from Iran as they step off the plane in Germany. Barry Rosen is second from the bottom waving with no glasses and a beard. He has just announced that he will be going back to Iran to meet with his captors. The hostages were kept over a year in captivity after the US Embassy was stormed during the Iranian Revolution. Relations with Iran and the US have been improving lately. (photo by Tim Chapman)
A Kurdish family having fled northern Iraq, carry all their worldly possessions, reach the border town of Nossod, Iran. Saddam Hussein crushed the Kurdish uprising in northern Iraq in the aftermath of 1991 Gulf War led by the US and allied forces. (Photo by Kaveh Kazemi/Getty Images)
Iranian President Mohammad Khatami, greets thousands of students during his speech at a university stadium in Tehran, Iran Sunday, Dec. 12, 1999. The stadium erupted in cheers when Khatami declared that his nation felt no enmity toward the American people. Iran-U.S. ties have been strained since Washington severed ties over the 1979 storming of the U.S. Embassy in Tehran by Islamic militants. Relations thawed after the May 1997 election of Khatami. (AP Photo/Hasan Sarbakhshian)
An Iranian woman pets a dove caged in the belly of a replica of the Statue of Liberty at the former US embassy compound November 3, 2001 in Tehran, Iran. Iranian authorities opened the former embassy to the public for the first time since the 1979 Islamic revolution toppled the US-backed Shah which ultimately led to the breaking of relations between Washington and Tehran. (Photo by Keivan/Getty Images)
Reza Pahlavi, son of the late Shah of Iran Mohammad Reza Shah Pahlavi, speaks to New York University students December 4, 2001 in New York City. Pahlavi spoke of the need to root out terrorism and the need for democracy in Iran. (Photo by Mario Tama/Getty Images)
An Iranian man teaches his son the 'death to America' chant during a demonstration after Friday prayers April 5, 2002 in Tehran. The protesters opposed the Israeli incursion into Palestinian-controlled territories. (Photo by Keivan/Getty Images)
Deputy Secretary of State Richard Armitage greets people before giving testimony before the U.S. Senate Foreign Relations Committee on Capitol Hill October 28, 2003 in Washington DC. The Committee is hearing testimony on security threats and the U.S. policy toward Iran. (Photo by Mark Wilson/Getty Images)
An Iranian girl rests during a meeting of the conservative group, the Coalition of Builders of Islamic Iran, in Tehran February 16, 2004. The group has taken a tough stance on the country's nuclear prerogatives and a moderate line on US-Iranian relations and the imposition of Islamic social regulations. The main reformist parties are staying away after a conservative-run political vetting body, the Guardians Council, barred some 2,300 people -- most of them reformists -- from even standing in the February 20 polls. (Photo credit: BEHROUZ MEHRI/AFP/Getty Images)
A man holds an effigy of U.S. President George W. Bush during a protest against the U.S.-led occupation of Iraq in Enqelab Square May 19, 2004 in Tehran, Iran. Demonstrators reportedly hurled petrol bombs, firecrackers and stones at the British embassy. (Photo by Majid/Getty Images)
This 18 January file photo shows Secretary of State-designate Condoleezza Rice testifying before the Senate Foreign Relations Committee during her confirmation hearing on Capitol Hill in Washington, DC. US Secretary of State Condoleezza Rice will discuss the war in Iraq and tensions with Iran when she meets Chancellor Gerhard Schroeder on 04 February 2005.(Photo credit: TIM SLOAN/AFP/Getty Images)
U.S. Senator Dick Lugar (R-IN) (C) speaks to the media after addressing the U.N. Security Council at the United Nations February 6, 2006 in New York City. Lugar, along with other Senate Foreign Relations Committee members George Voinovich (R-OH) (R) and Norm Coleman (R-MN), spoke on reform at the U.N., Iran and energy conservation. (Photo by Spencer Platt/Getty Images)
Iranian Foreign Minister Manouchehr Mottaki speaks during a meeting with relatives of the seven Iranian detainees arrested in Iraq by US forces, in Tehran, 18 May 2007. US troops seized seven Iranians in the northern Iraqi city of Arbil on 11 January from what Iran claims was an official consular building. Mottaki said after meeting the families of the detainees that Iran maintains that they were diplomats working for a 'consulate'. (Photo credit: ATTA KENARE/AFP/Getty Images)
Iranian students walk past an anti-US mural on the wall of the former US embassy in Tehran 24 October 2007. Twenty-eight years ago, 19-year-old Iranian chemistry student Massoumeh Ebtekar agreed to join other students in holding more than 60 Americans captive at their embassy in Tehran, an event that was to last 444 days and leave a rupture in US-Iranian relations that has yet to be healed. For Ebtekar, who was elected last year as a member of Tehran city council, there is no contradiction between her prominent role in the embassy siege and her efforts today for greater moderation in the Islamic republic. (Photo credit: ATTA KENARE/AFP/Getty Images)
A US soldier carries on March 1, 2008 a platter of mutton and rice offered to the troops by the mayor of the village of Nafet Khana on the Iraq-Iran border, which was destroyed during the 1980-88 Iraq-Iran war. An Iranian delegation left Baghdad for home today without holding talks with officials from archfoe the United States on the security situation in Iraq, an Iranian official said. Iran and the United States, which have had no diplomatic relations since 1980, held three rounds of talks about Iraq last year, but a fourth round scheduled for last month was postponed. AFP PHOTO/PATRICK BAZ (Photo credit should read PATRICK BAZ/AFP/Getty Images)
WASHINGTON, DC - July 09: Undersecretary of State William Burns testifies during the Senate Foreign Relations hearing on Iran. On the same day Iran test-fired missiles in a show of force in the Persian Gulf, the Bush administration Wednesday sought to downplay the country???s power and influence. ???For its part, Tehran seems to relish heightening concerns by promoting the illusion that Iran is on the ascendance,??? Undersecretary of State William Burns said in prepared testimony. ???However, Iran is not 10 feet tall, nor is it even the dominant regional actor.' (Photo by Scott J. Ferrell/Congressional Quarterly/Getty Images)
Holding an anti-Bush poster and pictures of Iranian late revolutionary founder Ayatollah Khomeini, left on the posters, and supreme leader Ayatollah Ali Khamenei, right on the posters, Iranians attend a demonstration in front of the former U.S Embassy in Tehran, Iran, Sunday, Nov. 4, 2007, in a ceremony commemorating the 28th anniversary of the seizure of the U.S. Embassy by militant students on Nov. 4, 1979. (AP Photo/Vahid Salemi)
Former National Security Advisers Brent Scowcroft, left, and Zbigniew Brezezinski arrive on Capitol Hill in Washington, Thursday, March 5, 2009, prior to testifying before the Senate Foreign Relations Committee hearing on U.S. strategy in Iran. (AP Photo/Harry Hamburg)
Japanese Akiko Saberi, mother of US-Iranian journalist Roxana Saberi, holds press cards and ID's for her jailed daughter at the family's house in Tehran on April 18, 2009. An Iranian revolutionary court has sentenced Roxana Saberi, 31, to eight years in jail on charges of spying for the United States, her lawyer said. AFP PHOTO/ATTA KENARE (Photo credit should read ATTA KENARE/AFP/Getty Images)
Iranian nuclear scientist Shahram Amiri stands with his father upon arrival at Imam Khomeini Airport in Tehran on July 15, 2010. Amiri, who claimed he was 'abducted' by US spies last year, denied that he was a nuclear scientist, but said he was questioned by Israelis during his 'harsh' captivity. Amiri had gone missing from Saudi Arabia in June 2009 while on a pilgrimage and surfaced in Iran's Interests Section in Washington on July 13, 2010. Upon his arrival in Tehran he immediately told reporters that he was just a 'simple researcher'. Iranian officials claim he was kidnapped by the Central Intelligence Agency of the United States. US officials have denied these accusations. AFP PHOTO / ATTA KENARE (Photo credit should read ATTA KENARE/AFP/Getty Images)
NEW YORK - JULY 30: (L to R) Laura Fattal, Cindy Hickey and Nora Shourd, mothers of three U.S. Citizens being detained in Iran, hold photos during a protest outside the Iranian mission to the United Nations on July, 30, 2010 in New York City. Josh Fattal, Shane Bauer, and Sarah Shourd, have been held by Irainian authorities since July 31, 2009 after they were detained along the Iraq and Iran border and accused of spying. (Photo by David Goldman/Getty Images)
NEW YORK, NY - SEPTEMBER 25: Josh Fattal (C) and Shane Bauer (R), two American hikers released after spending more than two years imprisoned in Iran, were joined by Sarah Shourd (L) and family members in front of a press-filled conference room at the Parker Meridien New York on September 25, 2011 in New York City. Fattal, Bauer, and Shourd were charged with trespassing and espionage, after allegedly crossing the border between Iraq and Iran on a hiking trip. (Photo by Michael Nagle/Getty Images)
Senator John McCain, a Republican from Arizona, right, and U.S. Secretary of State Hillary Clinton talk during a Senate Foreign Relations Committee nomination hearing in Washington, D.C., U.S., on Thursday, Jan. 24, 2013. Senator John Kerry stressed the need to prevent Iran from acquiring nuclear weapons. He described the 'immediate, dangerous challenges' facing the nation as he seeks confirmation to become secretary of state. Photographer: Andrew Harrer/Bloomberg via Getty Images
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Committee chairman Senator Bob Corker(L) , R-TN, and ranking member Senator Benjamin L. Cardin , D-MD, shake hands before a meeting of the Senate Foreign Relations Committee on Capitol Hill April 14, 2015 in Washington, DC. The committee met to debate and vote on S.615, the Iran Nuclear Agreement Review Act of 2015. AFP PHOTO/BRENDAN SMIALOWSKI (Photo credit should read BRENDAN SMIALOWSKI/AFP/Getty Images)
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USS Nitze had to change course in order to distance itself from the Iranian vessels, the official said, adding that the incident could have led to a diplomatic protest, but the United States does not have diplomatic relations with Iran.
It remains to be seen whether these actions were carried out by rogue Revolutionary Guard commanders or sanctioned by senior officials in Tehran, said Karim Sadjadpour, an Iran expert at the Carnegie Endowment for International Peace.
"For four decades the Revolutionary Guard have been told that America is the greatest threat to the Islamic Revolution," said Sadjadpour. "This institutional culture hasn't changed after the nuclear deal," he added.
In January, 10 U.S. sailors aboard two patrol craft were detained by the IRGC when they inadvertently entered Iranian territorial waters. They were released the next day after being held for about 15 hours.