For the first 30 minutes of the Democratic debate, the attacks in Paris loomed large, starting with a moment of silence and continuing with the opening statements.
The candidates were asked to address the attacks and what they would do in their opening statements, and former Secretary of State Hillary Clinton spent her entire opening statement talking about them.
She called ISIS a "barbaric, ruthless, violent jihadist terrorist group." And in an effort to remind the audience of what's a stake, she added, "This election is not only about electing a president. It's also about choosing our next commander in chief."
But Clinton, President Obama's former secretary of state, was on the defensive for part of the discussion, having to defend the Obama administration's record in the first question.
Moderator John Dickerson of CBS News pressed Clinton, using Obama's words that he didn't "think ISIS is gaining strength." Dickerson cited polling numbers that "72 percent of Americans think the fight against ISIS is going badly. Won't the legacy of this administration, which is-- which you were a part of, won't that legacy be that it underestimated the threat from ISIS?"
Clinton responded this way: "I think that we have to look at ISIS as the leading threat of an international terror network. It cannot be contained, it must be defeated."
That seemed to be a prepared line from Clinton, alluding to President Obama's interview on ABC Thursday, the day before the Paris attacks, in which he said, "From the start, our goal has been first to contain, and we have contained them."
Clinton later said, however, "This cannot be an American fight, although American leadership is essential."
President Obama's pursuit of a multilateral approach has been criticized by Republicans. And Democrats Saturday walked a very fine line on the tension between Obama's approach of a light footprint and placing a high value on multilateralism and the more interventionist and unilateral, if necessary, foreign policy most Republican candidates are advocating.
Former Maryland Gov. Martin O'Malley, like Clinton, also stuck to terrorism in his opening statement while also finding a way to hint at the main theme of his campaign. "This is the new sort of challenge, the new sort of threat that does, in fact, require new thinking, fresh approaches and new leadership," O'Malley said.
He later seemed to disagree with Clinton that the fight against ISIS "cannot be an American fight." And yet, he also seemed to contradict himself on what America should do about it.
"This actually is America's fight," O'Malley said, sounding like he was advocating for a more muscular approach. But then, he added, "It cannot solely be America's fight. America is best when we work in collaboration with our allies. America is best when we are actually standing up to evil in this world."
Clinton's principal rival for the nomination, Bernie Sanders, mentioned his shock and disgust at the attacks in Paris at the top of his opening remarks, but then quickly pivoted to his standard lines about income inequality.
"I'm running for president, because as I go around this nation I talk to a lot of people," the Vermont independent said. "And what I hear is people concerned that the economy we have is a rigged economy."
This may well have been a missed opportunity for Sanders to show more breadth. But his top adviser, in the spin room after the debate, defended Sanders' choice to quickly move on from terrorism in his opening statement.
"This campaign and his message is about rebuilding the middle class of America," said Sanders adviser Tad Devine. "And we knew there was going to be an extended, as it turned out a 32-minute discussion of [terrorism], which would follow immediately thereafter. So, I think what Bernie did was present his full message to the American people."
At one point, Dickerson of CBS, asked Sanders about an answer he gave in the first Democratic debate last month. In that debate, the candidates were asked what they considered to be the greatest national security threat facing the country, and Sanders said it was climate change.
"Do you still believe that?" Dickerson asked.
Sanders didn't flinch. "Absolutely," Sanders said. "In fact, climate change is directly related to the growth of terrorism. And if we do not get our act together and listen to what the scientists say you're gonna see countries all over the world-- this is what the C.I.A. says, they're gonna be struggling over limited amounts of water, limited amounts of land to grow their crops. And you're gonna see all kinds of international conflict."
His campaign sent out emails during the debate noting that the U.S. military has said the same.
President Obama, in fact, said in his State of the Union address this year, "No challenge — no challenge — poses a greater threat to future generations than climate change."
Sanders added that international terrorism is a major issue that must be addressed. But it was not something he was as comfortable addressing as the economic issues that are more in his wheelhouse. That presents a potential problem, because after moments of great tragedy, especially when it comes to national security, Americans look to their presidents for reassurance, strength and confidence.
Sanders, however, tried to turn foreign policy in his favor when talking about the war in Iraq. Clinton voted to authorize the war when she was in the Senate and now says it was a mistake. Sanders voted against it as a member of the House of Representatives, and he aimed to use this against Clinton in the debate.
"I would argue that the disastrous invasion of Iraq, something that I strongly opposed, has unraveled the region completely," Sanders said. "And led to the rise of Al Qaeda — and to — ISIS." He added later: "I don't think any sensible person would disagree that the invasion of Iraq led to the massive level of instability we are seeing right now. I think that was one of the worst foreign policy plunders in the modern history of United States."
An area where the candidates seemed to agree, and where they will likely take heat from Republicans later is rhetoric in how to describe ISIS and the perpetrators of terrorist attacks. Dickerson asked whether the US is at war with "radical Islam" and later asked Clinton is that is a term she doesn't use.
Clinton cited the language former president George W. Bush used after the 9/11 attacks.
"He basically said after going to a mosque in Washington, 'We are not at war with Islam or Muslims. We are at war with violent extremism,'" Clinton said. "And yes, we are at war with those people but I don't want us to be painting with too broad a brush."
Just 16 days after the Sept. 11, 2001 attacks, in which two planes flew into and brought down the Twin Towers in New York, Bush said the following in an address to airline employees in Chicago: "Americans understand we fight not a religion; ours is not a campaign against the Muslim faith. Ours is a campaign against evil."
Sanders said he didn't think the term is important. And O'Malley said he'd rather use the term "radical jihadis."
After the debate, Sanders advisers crowed about the war in Iraq being a key focus of the foreign policy section of the debate. This, they figured, works in the senator's favor. Meanwhile, Clinton's team felt their candidate showed her depth of knowledge and nuanced understanding of the nation's security challenges.
Quotes are based on rush transcripts. NPR will update if there are changes in finalized transcripts.