Democratic presidential frontrunner Hillary Clinton blasted Republican rival Donald Trump during a counterterrorism speech Wednesday.
Taking aim at Trump's recent comments on NATO being obsolete, Clinton said turning our back on the alliance "would reverse decades of bipartisan of American leadership and send a dangerous signal to friend and foe alike."
Trump has said in recent days that NATO is costing the US too much money and has suggested rethinking the alliance.
"I think NATO may be obsolete," Trump said in a Bloomberg interview. "NATO was set up a long time ago, many, many years ago. Things are different now. ... We're paying too much. As to whether or not it's obsolete, I won't make that determination."
Clinton advocated for the opposite approach, saying the US needs to strengthen its alliances. She said that turning our back on NATO partners would be playing right the hands of Russian President Vladimir Putin.
"Putin already hopes to divide Europe," Clinton said in her speech at Stanford University. "If Mr. Trump gets his way, it will be like Christmas in the Kremlin."
REALTED: Hillary Clinton potential running mates:
Hillary Clinton potential running mates, VPs
'It will be like Christmas in the Kremlin': Hillary Clinton blasts Donald Trump over NATO comments
The junior Democratic Senator from the swing state of Virginia could be a strategic selection for Hillary. Kaine also served as the governor of Virginia from 2006- 2010.
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The current U.S. Senator from Massachusetts is popular among progressive Democrats, and some even tried to draft her to run for president herself in 2016.
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Insiders believe that the senior U.S. Senator from Ohio could help Clinton increase her popularity with working-class voters, a group she has yet to win in a big way so far in primary contests.
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The U.S. Senator from New Jersey is both youthful and charismatic and would add racial diversity to a Clinton ticket.
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The current U.S. Secretary of Labor is considered a sleeper pick by many Democrats because he is not well known outside of D.C., but some believe his strength and popularity among union workers and other progressive groups could be an asset to Clinton's ticket.
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The former mayor of San Antonio and current U.S. Secretary of Housing and Urban Development has been rumored as a possible running mate for Clinton for months, but in May he said in an interview that the Clinton campaign hasn't talked to him about the role.
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Insiders confirmed that Clinton is definitely considering a woman as her vice presidential pick, and as U.S. Senator from Minnesota, Klobuchar has a seat Democrats would likely maintain. She's also been described as "by far" the most popular politician in her state.
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The Independent from Vermont has become Hillary Clinton's primary rival for the Democratic nomination, garnering a surprising amount of support. Bringing Sanders onto the ticket could help to unite both sets of supporters who have been split in Democratic primaries.
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A former 2016 rival of Hillary Clinton, and former Maryland governor, Martin O’Malley could help bring some executive experience, along with a slight youthful boost to the ticket.
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The Secretary of Agriculture since 2009, Tom Vilsack also served as the governor of Iowa from 1999 to 2007. Vilsack could bring some governing experience along with swing state influence.
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Colorado Gov. John Hickenlooper delivers his annual State of the State address to lawmakers and guests, inside the state legislature, in Denver, Thursday, Jan. 14, 2016. Hickenlooper called upon Republicans and Democrats to return to an era of civility and compromise in his address to the Republican-controlled Senate and the Democrat-led House. (AP Photo/Brennan Linsley)
Evan Bayh could bring a more right leaning brand of politics to the ticket. Bayh previously served as the junior U.S. Senator from Indiana from 1999 to 2011, and also as the 46th Governor of Indiana from 1989 to 1997.
While the likelihood of him agreeing to take on the veep job again might be low, Biden's popularity among Democrats would likely boost Clinton's chances.
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Hillary's husband is technically allowed to serve in the job, and some legal experts even think he'd be able to take office if necessary. Unfortunately for the diehard Clinton supporters, a Clinton-Clinton ticket will probably be a dream that never comes true.
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"It will make America less safe and the world more dangerous," she added.
Clinton noted that after the September 11, 2001, terrorist attacks, America's allies within the alliance supported the US.
"On 9/11, NATO treated an attack against one as an attack against all," Clinton said. "On September 12, headlines across Europe ... proclaimed we are all Americans. ... Now it's our turn to stand with Europe. We cherish the same values and face the same adversaries, so we must share the same determination."
She also called NATO "one of the best investments America has ever made."
After the speech, Trump responded on Twitter:
Just watched Hillary deliver a prepackaged speech on terror. She’s been in office fighting terror for 20 years- and look where we are!
Earlier in the speech, Clinton repeated previous attacks on one of Trump's rivals for the Republican presidential nomination, Texas Sen. Ted Cruz.
"It would also be a serious mistake to begin carpet-bombing populated areas into oblivion," Clinton said, referring to Cruz's calls for "carpet-bombing" terrorists in the Middle East.
She added: "Loose cannons tend to misfire. What America needs is strong, smart, steady leadership to wage and win this struggle."
Clinton's speech came a day after terrorist attacks hit Belgium. Attackers bombed a Brussels airport and metro station, killing 30 people and wounding more than 230. The terrorist group ISIS (also known as the Islamic State, ISIL, or Daesh) claimed responsibility for the attacks.