President Donald Trump said there’s a “psychological deadline” for Russian President Vladimir Putin to agree to a ceasefire with Ukraine.

“It's a psychological deadline. If I think they're tapping us along, I will not be happy about it,” Trump told reporters on Air Force One Sunday evening.

But whether Russia was doing so, Trump said “I don't know, I don't think so. I think he wants to make a deal.”

Trump has promised to end the war between Russia and Ukraine, his team holding talks with each country over the last several weeks. While Ukraine indicated a willingness for a ceasefire, Russia has yet to follow suit, outside of agreements the administration announced to pause attacks in the Black Sea and on energy infrastructure.

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The comments come after Trump expressed disappointment in Putin’s recent comments towards Zelenskyy. Trump threatened secondary sanctions on Russian oil if a deal is not able to be made and he believes Russia to be at fault, in an exclusive interview with NBC News’ Kristen Welker.

Trump told reporters though, he doesn’t think Putin will go back on his word.

“I was disappointed in a certain way some of the things that he said over the last day or two having to do with Zelenskyy because when he considers Zelenskyy not credible, he's supposed to be making a deal with him, whether you like him or you don't like him. So I wasn't happy with that,” Trump said. “But I think he's going to be good and I certainly wouldn't want to put secondary tariffs on Russia but, if they were put on, it would not be very good for them.”

AFP previously reported that Putin called for a transitional administration be put in place for Ukraine.

Ukrainian President Volodymyr Zelenskyy has called for more pressure on Russia, accusing it of intentionally delaying an agreement in order to carry on the war.

“We expect that the United States, Europe, and all our other partners who genuinely seek peace and guaranteed security will use all the necessary tools. Everyone needs diplomacy to succeed, except Putin. Therefore, pressure must be applied to him for diplomacy to succeed and for people's lives to be saved,” Zelenskyy said in his nightly address.

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Zelenskyy spoke with Finland Prime Minister Alexander Stubb following Stubb’s visit with Trump Saturday in Florida, which inlcuded the issue of Ukraine according to the Finnish leader’s office. Stubb encouraged a deadline be set for a ceasefire, floating the date of April 20th, Reuters reported the Finnish leader told reporters.

While Trump’s comments mark a sharper tone towards Russia in recent weeks, Trump also accused Zelenskyy of “trying to back out of the rare earth deal.”

“We made a deal on rare earth and now he's saying, well, you know, I want to renegotiate the deal. He wants to be a member of NATO. Well, he was never going to be a member of NATO. He understands that. So if he's looking to renegotiate the deal, he's got big problems,” Trump said.

Last month Trump and Zelenskyy expected to sign a critical minerals deal, which Trump viewed as a way to recoup defense aid provided to Ukraine, before their Oval office meeting broke down.

In mid-March, White House press secretary Karoline Leavitt told reporters, “now we have moved beyond the economic minerals deal. We are at a place of peace. We're at a partial cease fire, and we're moving towards a full cease fire and a long standing peace in this conflict. And that's great news for the American public."