The Trump administration veered toward deeper conflict with Russia Tuesday as Secretary of State Rex Tillerson arrived in Moscow, gambling that an unpredictable new president armed with the willingness to threaten military action gives the U.S. much-needed leverage to end Syria’s carnage.

Yet there were no guarantees Tillerson’s arguments would prove any more successful than the Obama administration’s failed effort to peel Russia away from its Syrian ally. Tillerson’s mission, coming days after 59 Tomahawk missiles struck a Syrian air base, also carries serious risks: If Russia brushes off the warnings, President Donald Trump could be forced into another show of force in Syria or see his credibility wane.

“I hope that what the Russian government concludes is that they have aligned themselves with an unreliable partner in Bashar al-Assad,” Tillerson said before flying to the Russian capital, referring to Syria’s embattled leader.

“The reign of the Assad family is coming to an end,” he confidently predicted.

But Tillerson’s claim is one President Barack Obama, too, argued for years, only to see Assad outlast his own term in office. And the Trump administration’s nascent Syria policy seems to be increasingly centering on the same tactic Obama unsuccessfully employed: persuading Russia, Assad’s staunchest ally, to abandon him.

The parallels haven’t gone unnoticed by Russian President Vladimir Putin as U.S. officials have accused his military of knowing about Assad’s recent chemical weapons attack ahead of time and trying to help cover it up. Calling for a U.N. investigation, Putin held to his claim that it was actually Assad opponents who introduced chemical weapons into Syria’s harrowing civil war.

“We have seen it all already,” Putin said. Jabbing at U.S. credibility, the Russian leader reminded reporters about unfounded U.S. claims of Iraqi weapons of mass destruction, used to justify America’s 2003 invasion.

The escalating dispute over last week’s events in the Syrian town of Khan Sheikhoun has thrust Washington and Moscow into a level of tension rarely seen since the end of the Cold War. The animosity is especially striking given widespread speculation that Trump, who lavishly praised Putin during his campaign, would pursue rapprochement with Moscow.

Even on Syria, the positions appeared to be hardening. Only a week ago, top Trump officials had spoken off deprioritizing past U.S. efforts to remove Assad from office and accepting the “reality” that 18 months of Russian military intervention had secured him in power. Since last Thursday’s cruise missile strike, Tillerson and other U.S. officials appear to have reverted to the past administration’s rhetoric of insisting that Assad is on the way out, without outlining any strategy for making that happen.

The Trump administration’s change of heart, apparently spurred in part by the president’s emotional response to the images of chemical weapons victims, also is serving another purpose: defanging the perception of coziness between Trump and Moscow. As the FBI and multiple congressional committees investigate potential collusion between Russia and Trump’s campaign, the president can point to his hard-line stance on Assad as fresh evidence he’s willing to stand up to Putin.

Asked about Putin possibly skipping a meeting with Tillerson, White House press secretary Sean Spicer said, “There is a bit of irony that for all of these talks that have been perpetuated about back channels and direct links, that now it’s they won’t meet with you.” At a minimum, Tillerson will meet Wednesday with Russian Foreign Minister Sergey Lavrov, and the two are expected to take questions from reporters.

As Tillerson landed in Moscow, senior White House officials briefed reporters on declassified U.S. intelligence they said disproved Russia’s claim that rebels were responsible for the chemical weapons. In an accompanying four-page memo, the U.S. accused Russia of a disinformation campaign and aiding Syria in covering up the gruesome attack, which killed more than 80 people.

“Russia’s allegations fit with a pattern of deflecting blame from the regime and attempting to undermine the credibility of its opponents,” the report read.

Defense Secretary Jim Mattis told reporters at the Pentagon, “It is very clear who planned this attack, who authorized this attack and who orchestrated this attack.”

Putin’s government has been incensed by the Trump administration’s public accusations, and even more so by U.S. military intervention in Syria. The retaliatory strikes, which Obama declined to approve after blaming Assad for an even deadlier chemical weapons attack in 2013, hit an air base where Russian troops were also present, although none are believed to have been killed.

Meeting allies earlier Tuesday in Italy, Tillerson delivered an ultimatum to Russia: Side either with the U.S. and its dozens of coalition partners or face the isolation of a partnership with Assad, Iran and Hezbollah. That may hardly be punishment for the Kremlin, which dismissed many of Obama’s similar warnings about Russia being sucked into a quagmire in Syria with no way out while tarnishing its international reputation.

Trump may not have much to offer Russia currently. Even if Moscow cooperates, the allegations of election meddling have weakened the U.S. leader’s hand to deliver on any significant carrot, such as a loosening of the U.S. and European economic sanctions stemming from Russia’s actions in Ukraine.

And wielding the stick of potential military action is risky. Trump’s cruise missile order restored the believability of Washington using its military might in Syria.

But if Moscow ignores Trump’s entreaties or if Assad uses chemical weapons again, bad options await Trump. He can order more military action, with the danger of an escalating America involvement in a war that has killed hundreds of thousands of people. Or he can hold back and risk losing face like Obama.

Putin seems undeterred. Hours after Tillerson’s warning, his office announced Russia would host Syria and Iran’s foreign ministers for a three-way meeting Friday, the day after Tillerson departs.