Donald Trump says American efforts to bring Russia and Ukraine to peace are going “fine,” but appears cognizant that Russian President Vladimir Putin may be only pretending to engage in good faith.

“We’ll find out whether or not he’s tapping us along or not and if he is, we’ll respond a little bit differently but it will take about a week and a half to two weeks,” the U.S. president said Wednesday in response to reporters’ questions at the White House. “They seem to want to do something, but until the document is signed I can’t tell you. Nobody can.”

“I can say this: I’m very disappointed at what happened a couple of nights now, where people were killed, in the middle of what you would call a negotiation,” he continued, adding later: “When I see rockets being shot into cities, that’s no good. We aren’t going to allow it.”

Russia has stepped up its bombardment of Ukraine in recent weeks, despite a successful prisoner swap conducted late last week.

Trump, who has previously been an open admirer of Putin, has become more critical of the Russian president amid the drone and missile attacks, calling him “CRAZY” and opining that he is “playing with fire.”

When asked about his decision to not impose new sanctions on Russia, he said: “If I think I’m close to getting a deal I don’t want to screw it up by doing that, let me tell you, I’m a lot tougher than the people you’re talking about, but you have to know when to use that.”

“If I think it’s going to hurt a deal — this isn’t my war, this is Biden’s war, Zelenskyy’s war, Putin’s war. This isn’t Trump’s war.”

Russia invaded Ukraine in early 2022. Hundreds of thousands of soldiers on both sides of the conflict have been killed.

Earlier Wednesday, the U.N. concluded that Russia has been systematically committing war crimes against civilians in Ukraine’s Kherson region.