In the early hours after President Donald Trump ordered a drone strike that killed Iran’s top military official, the Democratic presidential field responded in lockstep that the operation had the potential to destabilize the region further and put the lives of Americans and their allies at risk of deadly reprisal.

But as the potential blowback against the United States became clearer in the days following the death of Major General Qassem Soleimani, the leader of the Iranian Quds Force and architect of Iran’s war against ISIS across the region, candidates began to divide themselves into two camps: those who argue that only a steady, experienced hand can steady America’s increasingly erratic foreign policy, and those who point to the past two decades of U.S. foreign policy to show the need for drastic change.

Former Vice President Joe Biden, whose entire presidential campaign centers on the restorationist idea that his decades of Washington experience are the best guarantee to undo the Trump administration’s mistakes, has been increasingly nudged closer to the fire by opponents pointing to his past support for the invasion of Iraq and the subsequent occupation, a quagmire from which many of the current crises in the region emerged. As a former two-term vice president and a major figure in U.S. foreign policy during his decades in the Senate, Biden is particularly vulnerable to attacks on geopolitical orthodoxy as an example of what not to do.

“Age does not necessarily correlate with wisdom on foreign policy,” one foreign policy adviser to a top-tier campaign told The Daily Beast. “Over the course of years, and in some cases decades, there is a track record that is extensive—and in some cases it is consistent—in pointing to flaws of judgement, and perhaps even a worldview that is not necessarily well-suited to what is required of a commander in chief.”

Leading the charge, unsurprisingly, is Sen. Bernie Sanders of Vermont, who for years has trumpeted his 2002 vote against authorizing the use of military force in Iraq as a member of the House of Representatives as evidence that decades of foreign policy experience can’t supplant good judgment. Even in the days before the strike that killed Soleimani when foreign policy was still very much on the back burner for most presidential hopefuls, Sanders had described Biden’s support for the war as “a lot of baggage.”

“I was right about Vietnam. I was right about Iraq. I will do everything in my power to prevent a war with Iran,” Sanders tweeted on Friday morning, alongside a video underscored by a trap beat in which he describes that war and the vote that authorized it as “the worst foreign policy blunder in the modern history of the United States.”

“People want to criticize me for that? Go for it, that’s okay,” Sanders said. “I don’t apologize to anybody.”

Sen. Elizabeth Warren (D-MA) and former Mayor Pete Buttigieg, both of whom entered politics long after public opinion and political consensus turned against the invasion of Iraq, have been more implicit in their criticism, instead warning that Soleimani’s death risks an escalation of military tensions with Iran that could result in another “endless war”—like the one Biden voted for.

“Every piece of this is about judgement,” Warren said on CNN’s State of the Union on Sunday, when asked whether Biden should be the most trusted candidate on foreign policy matters despite his past support for the Iraq War, as polls of likely voters have suggested. “There are people running for president who are willing to keep combat troops in the Middle East for five years, for 10 years… Staying pinned down and escalating our wars in the Middle East is not in the long-term interest of the United States.”

“ There is a track record that is extensive—and in some cases it is consistent—in pointing to flaws of judgement, and perhaps even a worldview that is not necessarily well-suited to what is required of a commander-in-chief. ” — Democratic foreign policy adviser

Warren has not been immune from criticism for her own response to Soleimani’s killing. Her campaign’s initial statement in response to the strike, calling the late Quds Force chief a “murderer, responsible for the deaths of thousands,” was criticized from the left as parroting the talking points of more hawkish Democrats. Warren on Sunday morning dodged the question of whether she still felt that Soleimani’s death amounted to an assassination, responding that “the question that we ought to focus on is, why now?”

On the same program, Buttigieg declined to directly question Biden’s judgement on foreign policy matters, telling host Jake Tapper that the focus should be on Trump, his decision-making process ahead of ordering the operation, and as The Daily Beast reported on Saturday, his decision to gossip about impending military action with members of his private Palm Beach resort.

“I’ll let the V.P. speak to his own judgment,” Buttigieg said, noting that his judgement is informed by his experience as a naval intelligence officer in Afghanistan. But earlier in the week, before most Americans or candidates likely even knew who Soleimani was, Buttigieg had blasted Biden’s vote as supporting “the worst foreign policy decision made by the United States in my lifetime.”

“You could also argue that we wouldn’t be there if it weren't for the invasion of Iraq in the first place, which I still believe was a grave mistake,” Buttigieg later told reporters in New Hampshire on Friday.

Buttigieg and Warren’s more abstract criticisms of Biden’s judgement, the foreign policy adviser told The Daily Beast, harken back to a day when differences on geopolitics weren’t marks of personal failure—so long as you learned from your mistakes.

“A lot of this has gone out the window, but there’s a hope where we can get back to a point where these positions and approaches can transcend politics, where they’re not personalized, not politicized, but based on principles and values,” the adviser added.

The Biden campaign, however, told The Daily Beast that they see the emergence of foreign policy matters as a central issue in campaign politics as a boon, rather than a burden.

“These events put into greater relief that we need a commander-in-chief who can, from the moment they’re sworn in—and without needing on the job training—start repairing the severe damage that Donald Trump has done on the world stage,” a campaign spokesperson told The Daily Beast.

One campaign that has felt no compunction about explicitly personalizing Biden’s past potential liabilities on the Middle East is that of Trump himself. In the hours after Soleimani’s killing, Trump campaign officials declared that Biden’s track record in the region was both too bellicose and too simpering.

“America's enemies in Iran rejoiced under Obama/Biden,” tweeted Trump campaign director of rapid response Matt Wolking. “Under Trump, they are crying like babies.”

The Trump campaign also pushed out an old interview with former Secretary of Defense Robert Gates, who served under President Barack Obama, in which he stood by saying that he thought Biden had been “wrong on nearly every major foreign policy and national security issue over the past four decades.”

Biden’s response, as in other campaign moments when his buttons were pressed, has been defensive to the point of inelegance, refusing to respond to Sanders’ comments about his “baggage” except to say that Sanders himself has more than his fair share.

On Friday, Biden’s response to a reporter’s inquiry about his role in the 2011 operation that led to the death of Osama bin Laden prompted further questions about whether his foreign policy experience is a help or a hindrance. In an exchange with Fox News correspondent Peter Doocy, Biden said that he would be willing to use an airstrike to kill a terrorist leader, using the bin Laden operation as an example. When Doocy followed up by noting that Biden has previously said that he discouraged President Obama from authorizing the operation, Biden brusquely responded, “No, I didn’t. I didn’t.”

The exchange—which was almost instantly repackaged by the Trump campaign into an email titled “Joe Biden just lied about opposing the raid to kill Osama bin Laden”—sparked a flurry of fact-checking articles noting that by all accounts, including Biden’s own in 2012, he had not backed the operation in a group meeting at the time. In 2015, Biden said that he did not offer a firm opinion in that group meeting, saying that “it would have been a mistake” to do so, but that he had privately encouraged President Obama to “trust your gut.”

A Biden campaign official confirmed to The Daily Beast that Biden had told Obama in a private conversation that he supported the president following his “instincts” on the raid, and noted that that aspect of Biden’s story has never changed.

Biden, for his part, is hoping to keep the focus on the more pressing matter of Trump’s foreign policy, rather than his own.

“No president has a right to take our country to war without the informed consent of Americans—informed consent. And right now we have no idea what this guy has in mind, we have no idea,” Biden told reporters before a campaign event in Des Moines, Iowa, on Saturday evening. “He's going off on a tweetstorm on his own, and it's incredibly dangerous and irresponsible.”