During last year’s presidential campaign, Donald Trump and Hillary Clinton had heated debates over Syria. Clinton took a hardline stance, advocating more airstrikes against the Islamic State and the enforcement of no-fly zones, even at the risk of clashing with President Bashar al-Assad’s ally in the conflict, Russia. Trump countered by arguing that if defeating ISIS was so important, the United States should be willing to work with anyone. “I don’t like Assad at all, but Assad is killing ISIS,” Trump said during his second debate with Clinton. “Russia is killing ISIS. And Iran is killing ISIS.... I think you have to knock out ISIS.”

Trump was, in effect, calling for a grand alliance against the Islamic State, but it’s become abundantly clear that this is not to be. Instead, the president is undergoing a remarkable transformation on Syria: He’s rapidly turning into Hillary Clinton, and it’s making a major U.S. war more likely.

Though Trump derided such an approach in debates with Clinton, the U.S. is now fighting a multi-pronged war in Syria, as opposed to focusing exclusively on ISIS. In April, after a chemical weapons attack by Assad forces, Trump ordered a missile strike on a military airfield—a harbinger of a shift in policy, it now seems. Over the past week, the U.S. has downed two Iranian-built drones, and on Sunday the military shot down a Syrian jet—the first time the U.S. has done so in this war. In response, the Russian government suspended its air-traffic hotline with the U.S. and warned that it might target U.S. and allied planes if they fly west of the Euphrates.

Four direct engagements w Syria/Iran/Russia in 45 days. Trump is quietly starting a new war that Congress has not declared. Red alert. 🚨 https://t.co/D4MKPLXFTS — Chris Murphy (@ChrisMurphyCT) June 19, 2017

The U.S. now finds itself in a much more dangerous situation in the Middle East, where the war against ISIS, which has broad bipartisan support, could become a wider regional conflict of the type that Trump specifically promised to avoid.

This shift is partially a response to success on the field. ISIS is in retreat, and expected to lose its strongholds in Mosul (in Iraq) and Raqqa (in Syria). Thus, the various factions fighting ISIS have no reason to form the alliance that Trump hinted at. Instead, they are already preparing for a post-ISIS world by securing as much territory as they can. For Iran in particular, the end of ISIS would be their biggest unexpected bounty since the early days of the George W. Bush administration, when the U.S. obligingly removed Saddam Hussein and the Taliban from power in Iraq and Afghanistan, respectively. With ISIS out of the picture, Iran would have an unbroken swath of allies from Iraq to Syria to Lebanon—a land bridge to Israel’s border.