Key takeaways from Trump and Zelenskyy's meeting, pivotal talks with European leaders

President Donald Trump and Ukrainian President Volodymyr Zelenskyy sounded positive as they met at the White House on Monday as Trump pushes for an end to Russia's war on Kyiv.

Zelenskyy was joined in Washington by a remarkable delegation of European leaders who rushed to the U.S. in support of the Ukrainian leader in the wake of Friday's talks between Trump and Russia's Vladimir Putin in Alaska.

The last time Zelenskyy was in the Oval Office was February, when he received a verbal lashing from President Trump and Vice President JD Vance, who accused him of not being grateful enough for U.S. military assistance.

Monday's meeting was a much more cordial affair, with Trump and Zelenskyy sharing smiles and Zelenskyy thanking the president for his personal efforts to bring this conflict to a close.

Afterward, they sat down with European leaders, who before news cameras pressed Trump publicly on the need for security guarantees for Ukraine as part of any deal -- after Trump made a new commitment on that point. Some also said a ceasefire would be necessary before further negotiations or any trilateral meeting between Trump, Zelenskyy and Putin.

Here are some key takeaways from the high-stakes meetings.

President Trump on Monday said the United States will be involved in security assistance for Ukraine but did not elaborate on what exactly that would look like or give any specifics.

"We're going to be discussing it today, but we will give them very good protection, very good security," Trump said.

The president later confirmed that Putin said Russia would accept security guarantees for Ukraine.

Trump didn't go quite as far as special envoy Steve Witkoff, who told CNN that Russia agreed to "Article 5-like" protections. Article 5 is the agreement of collective defense among NATO nations stating an attack against one member is considered an attack against them all.

Trump said Europe would need to shoulder much of the burden when it comes to security guarantees, but that the U.S. will play a role.

"They are first line of defense because they're there," Trump said before adding, "But we're going to help them. And also we'll be involved."

After previously pushing for a ceasefire and threatening severe consequences for Russia if Putin did not stop the war, President Trump appeared to back off that demand.

"I don't think you need a ceasefire," he said in the Oval Office. "I know that it might be good to have, but I can also understand strategically, like, well, you know, one country or the other wouldn't want it."

He continued that he likes "the concept of a ceasefire for one reason, because you'd stop killing people immediately."

Trump continued to push for a trilateral meeting between himself, Zelenskyy and Putin -- something he had hoped to set up immediately following his summit with Putin on Friday but was unsuccessful.

Zelenskyy said Ukraine is "ready" for a trilateral discussion.

"I think it's going to be when," Trump said, "not if."

Trump and Zelenskyy sat down with a host of European leaders in the East Room following their bilateral talks in the Oval Office.

At the table were NATO Secretary General Mark Rutte, European Commission President Ursula von der Leyen, French President Emmanuel Macron, German Chancellor Friedrich Merz, United Kingdom Prime Minister Keir Starmer, Italy Prime Minister Giorgia Meloni and Finland President Alexander Stubb.

Nearly all the leaders stressed the need for security guarantees for Ukraine, with several saying it should look similar to Article 5 obligations. Ukraine is not a member of NATO but the nation has pushed for membership, something Russia is strongly opposed to.

"The fact that you have said that I'm willing to participate in the security guarantees is a it's a big step. It's really a breakthrough," NATO's Rutte told Trump. "And, it makes all the difference. So also, thank you for that."

France's Macron and Germany's Merz challenged Trump on a ceasefire, insisting it's a necessity for moving forward.

"The next steps ahead are the more complicated ones now ... To be honest, we all would like to see a ceasefire," Germany's Merz said. Merz said he cannot imagine a trilateral meeting would be able to occur without a ceasefire in place.

Trump said he will call Putin after his meetings Zelenskyy and European leaders at the White House.

"We're going to have a phone call right after these meetings today, and we may or may not have a trilat. And if we don't have a trilat, then the fighting continues. And if we do, we have a good chance -- I think if we have a trilat that there's a good chance of maybe ending it," Trump said.

"But he's expecting my call when we're finished with this meeting," Trump added of Putin.

ABC News' Meredith Deliso contributed to this report.