Democratic presidential candidate Hillary Clinton is escalating her criticism of rival Sen. Bernie Sanders over the issue of foreign policy, attempting to depict him as a novice on the issue.
In a Democratic primary that appears to be tightening, Clinton has sieged on her experience as someone who has a deep understanding of the nuances of foreign policy from her time as the country's top diplomat. At the same time she is painting Sanders as a neophyte who doesn't have a grasp on the complexities of the world.
Sanders, who has built a career focused on economic issues, is attempting to minimize his perceived weakness. He released a campaign ad promoting his views and record on foreign conflicts, including the war in Iraq and ISIS.
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Outside of his new ad, Clinton said at a campaign rally in Indianola, Iowa Thursday that Sanders is mostly trying to avoid the issue.
"Sanders doesn't talk very much about foreign policy, but when he does, it raises concerns because sometimes it can sound like he hasn't really thought it through," Clinton said. "The challenges a president has to grapple with are beyond complicated, both at home and abroad. That's why it's the hardest job in the world. I've seen it up close and personal and I know what it takes."
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Clinton's comments echo a two-and-a-half-minute video her campaign released earlier in the day featuring Jake Sullivan, her top foreign policy adviser who worked for her during her tenure at the State Department.
"When you look at all these ideas it's pretty clear he just hasn't thought it through," Sullivan said after listing some of Sanders' foreign policy positions.
Clinton has been drawing attention to a comment Sanders made in Sunday's NBC News Democratic debate when he said, "I think what we've got to do is move as aggressively as we can to normalize relations with Iran."
That shows a level of naiveté, Clinton insists. In an interview with NPR Wednesday, Clinton drew attention to his position, calling it a "fundamental misunderstanding of what it takes to do the patient diplomacy that I have experience in."
After noting that Iran "seeks the destruction of Israel" and is "flouting international law with its ballistic missile threats," Sullivan said in the video, "it's not at all clear why it is Sen. Sanders is suggesting it."
In a conference call held for reporters Thursday, Sullivan reiterated his concern, saying normalizing relations with Iran is "a bridge too far" even for supporters of diplomatic relations with Iran.
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At Sunday's debate, just moments after Sanders said he supports moving "aggressively" to normalize relations, however, he added more caution. "Can I tell that we should open an embassy in Tehran tomorrow? No, I don't think we should. But I think the goal has go to be as we've done with Cuba, to move in warm relations with a very powerful and important country in this world," he said.
Clinton immediately responded. "We've had one good day over 36 years and I think we need more good days before we move more rapidly toward any kind of normalization," she said.
Sanders campaign did not respond to request for a response to this attack.
Sanders, who has focused much of his career on an economic platform, is attempting to minimize his perceived weakness on foreign policy. After issuing concerns that a debate shortly after the Paris attacks would focus on foreign policy, he has since been more willing to discuss the issue. When the discussion turns to foreign policy in debates, he almost immediately brings up Clinton's support for the Iraq War - a war Sanders didn't support. It's an issue that damaged her campaign in 2008.
He even attempted to go on the offense with a new television ad in early voting states. The ad doesn't mention Clinton but is an attempt to boost his foreign policy credentials. It opens with his opposition to the Iraq War and goes on to say that "ISIS should be destroyed" but with an international coalition. Sanders closes the ad with, "It's time to end the quagmire with perpetual war in the Middle East."
But Clinton is being specific with her criticisms.
"For example, he suggested we invite Iranian troops into Syria," Clinton said at the Iowa rally. "That is like asking the arsonist to be the firefighter. As bad as things are in Syria, and they are, more Iranian troops are only going to make it worse."
This article first appeared on NBCNews.com.