U.S. Secretary of State Rex Tillerson has a difficult job when he heads to Moscow next week. His Russian counterpart, Sergey Lavrov, has already compared the U.S.’s rationale for strikes in Syria—a sarin gas attack on civilians earlier in the week widely attributed to the Assad regime—to the flawed evidence the U.S. presented to the UN Security Council in 2003 to successfully make the case for the war in Iraq. And Tillerson said after the U.S. strikes that Moscow had “failed in its responsibility” to deliver on a deal it brokered with the U.S. to destroy Syria’s chemical-weapons stockpile, calling Russia either “complicit, or … simply incompetent.”

Russia will almost certainly be an obstacle to any planned U.S.-led action in Syria. Its own military is involved in the Syrian Civil War, supporting President Bashar al-Assad, so an escalation in U.S. military action is considered highly unlikely—unless the Trump administration is willing to draw a Russian response. Then there is the question of action by the UN Security Council, which could lend a global imprimatur to the U.S. action Friday (Thursday night in the U.S.), or simply issue a condemnation of the Assad regime’s use of chemical weapons. Russia, one of the five permanent members of the council, is likely to veto those attempts. Russia’s account of the chemical-weapons attack also differs from that of Western governments. It says Syrian aircraft hit a rebel facility that was making chemical weapons, affecting civilians nearby.

But Tillerson’s remarks about the U.S. view of Assad suggests the U.S. is likely to pursue a diplomatic path—and that its focus will remain ISIS, which the U.S. has targeted in Syria since at least 2014.

“ Overall, the situation in Syria is one where our approach today and our policy today is first to defeat ISIS,” he said Thursday night in Florida after the strikes. He said that would be followed by an effort to stabilize Syria and restore the country to local government. “In the midst of that … we will start a political process to resolve Syria’s future in terms of its governance structure,” he said. “And that ultimately, in our view, will lead to a resolution of Bashar al-Assad’s departure.”

In other words, Assad’s departure will be sought through diplomacy. That might be a position Russia could sign onto. A Kremlin spokesman told the Associated Press on Thursday, before the strikes, in reference to Assad, that “unconditional support is not possible in this current world.”

U.S. allies are more likely to sign on to any next steps—whether diplomatic or military. The Obama administration was circumspect about the use of force against Assad despite pleas from U.S. allies in Europe and NATO, who’d called for a more forceful response to Assad’s actions against his own people that have resulted in hundreds of thousands killed and a massive humanitarian crisis that has had political consequences in Europe. Trump with his missile strikes has shown he won’t hesitate to act—though it’s unclear what the next steps exactly are.

Trump said the U.S. strikes targeted a Syrian airbase from where Assad’s air force had taken off to bomb targets with chemical weapons. But with this attack by Assad merely being the latest to use such weapons, it’s unclear whether the U.S. will act every time there’s such an attack—or if there are more images of dead children, which the president said had moved him to action. Nor is it clear whether another enforcement mechanism—such as the one the U.S. and Russia attempted in 2013 to destroy Syria’s chemical-weapons stockpile—can work. Despite that agreement, which was monitored by international inspectors from the Organization for the Prohibition of Chemical Weapons (OPCW), Assad has used chlorine against civilians. Of course, the U.S. strikes might chasten Assad, even if he can still count on Russia’s support, as he will now be wary of additional possible U.S. action against him.

The U.S. strikes could embolden rebels fighting Assad. Most of the moderate rebel groups are engaged in a fragile cease-fire with Assad, brokered by Russia, Iran, and Turkey. ISIS and al-Qaeda linked groups aren’t part of the truce. The Free Syrian Army, which is part of the cease-fire, called the strikes “welcome news.” There are two ongoing efforts to end the more than six-year-long civil war: the Geneva process, which has had marginal success and which involves the UN, the Syrian government, and some opposition groups; and the Turkey- and Russia-brokered talks in Astana that came after the cease-fire declaration late last year. It’s unclear what the U.S. strikes mean for the truce or either of these efforts.