Wilmington, North Carolina (CNN) Sen. Tim Kaine sought Tuesday to dismantle Donald Trump's national security credentials, slamming the GOP nominee for a "bizarre fascination" with strongmen and highlighting his shifting positions on the Iraq War.

Hillary Clinton's running mate framed Trump an "untested candidate," calling him "emotionally volatile, fact-challenged, self-obsessed and inexperienced."

"He has a bizarre fascination with strongmen and authoritarian leaders in countries that are no allies of the United States, and with respect our allies, he would toss alliances aside, and says he wants to, quote, 'Take everything back from the world that we've given them,'" Kaine said, speaking here at a historic USO building.

Trump has expressed praise and expressed admiration for Russia's Vladimir Putin, Libya's Moammar Gadhafi, and North Korea's Kim Jong Un, among others, in the past. He has said Putin "is a leader, unlike what we have in this country," believed Gadhafi was effective at killing terrorists and praised the young North Korean leader's rise to power, saying, "It's pretty amazing when you think of it."

The Democratic vice presidential nominee, who is a member of the Senate Armed Services and Foreign Relations committees and has a son serving abroad in the Marine Corps, flexed his foreign policy muscles in remarks primarily focused on Clinton's Republican rival and the contrasts between the two candidates on national security.

The push is part of a campaign focus of hitting Trump on national security, according to Clinton aides speaking on condition of anonymity to discuss strategy. They noted early voting begins in many states this month, and Clinton relishes going after Trump on the topic because she feels like she knows it well and he doesn't.

At Tuesday's speech, Kaine called out Trump for his shifting stance on the Iraq War, saying he "misled" voters about his position.

"In Trump's first campaign speech, he claimed that he'd had the foresight to say, 'Don't hit Iraq,' because you're going to completely destabilize the Middle East ... It's one of the main rationales for his candidacy. And it's completely made up," Kaine said.

"These days, he rails against the decisions to pull troops out of Iraq, a decision set in motion by the Bush administration, claiming that that decision led to the creation of ISIS. So here's the problem: In 2006, Trump believed we weren't pulling our troops out of Iraq fast enough. He said we should, quote, 'Get out of Iraq as quickly as possible.'"

He poked the billionaire's credentials further, knocking him as a "TV star."

"Trump has misled the American people over and over about his position on Iraq. He was for invading Iraq. And then he decided he wasn't. He was for leaving Iraq. And then he decided he wasn't. He says whatever he feels like at any given time because you can do that when you're a TV star. But you can't do that when you're president of the United States."

Kaine also chided Trump for his meeting last week with Mexican President Enrique Peña Nieto, with whom he later entered into an online spat over whether they discussed if Mexico would pay for a wall along the US-Mexico border.

"Just hours after his first international foray into foreign relations, Trump was in an online feud with one of our neighboring heads of state, our second largest trading partner," Kaine said. "Now, if you're going to get into a feud with an ally, how about dealing with an adversary? I guess we should be glad it was only a Twitter war, because In a few months, he could have control of the armed forces."

Kaine has increasingly stepped into the role of vice presidential attack dog for Clinton in recent days. Late last month, he said Trump was "pushing" the values of the Ku Klux Klan. He backed away from the comments a day later, telling reporters that Trump has some supporters "connected" with the KKK who are "claiming him."