After falling short on his campaign promise to quickly end the Ukraine crisis, the Trump administration has repeatedly warned that it may withdraw from its mediation efforts if there's no progress toward ending the conflict.

WASHINGTON/MOSCOW, May 20 (Xinhua) -- Ceasefire negotiations between Russia and Ukraine "will begin immediately," said U.S. President Donald Trump after his two-hour call with his Russian counterpart, Vladimir Putin, on Monday, noting that "the tone and spirit of the conversation were excellent."

Upbeat as he is, the talk remains "inconclusive," with little sign of a breakthrough, said U.S. media, as the timing, location and participants of any negotiations remain unclear.

WHAT DID TRUMP SAY?

Right after his phone call with Putin, Trump posted on his social media Truth Social that Russia and Ukraine will "immediately start negotiations toward a ceasefire," and work to end the conflict.

He said Russia is eager to pursue major trade deals with the United States once the conflict ends. "There is a tremendous opportunity for Russia to create massive amounts of jobs and wealth. Its potential is UNLIMITED. Likewise, Ukraine can be a great beneficiary on Trade, in the process of rebuilding its Country."

He added that the ceasefire conditions will be negotiated between Russia and Ukraine, "as it can only be, because they know details of a negotiation that nobody else would be aware of."

However, when speaking to reporters later, Trump warned that he could back out of the negotiation process. "Big egos involved, but I think something's going to happen. And if it doesn't, I just back away, and they're going to have to keep going again," he said.

After falling short on his campaign promise to quickly end the Ukraine crisis, the Trump administration has repeatedly warned that it may withdraw from its mediation efforts if there's no progress toward ending the conflict.

U.S. Vice President JD Vance reiterated such warnings ahead of Trump's call with Putin. "We realize there's a bit of an impasse here ... The United States is not going to spin its wheels here. We want to see outcomes," he said.

"I'm not sure that Vladimir Putin has a strategy himself for how to unwind the war," Vance added, while Trump later told reporters that he believed Putin was serious about wanting peace.

Trump also said that holding the peace talks at the Vatican, as represented by the Pope, would "have some extra significance."

Pope Leo XIV noted efforts to end the Ukraine conflict at his inaugural mass on Sunday and held a meeting with Zelensky. The newly elected pontiff had called for an end to the conflict in his first days in office.

Earlier this month, the Pope offered the Vatican as a potential site for peace talks between Russia and Ukraine, after Putin declined to meet Zelensky face-to-face in Trkiye for negotiations. Eventually, neither president showed up at the negotiation table on Friday in Istanbul, where the two sides agreed to a swap of 1,000 prisoners of war but failed to reach a deal on an immediate ceasefire.

PUTIN AND ZELENSKY'S REMARKS?

In contrast to his enthusiasm, Putin offered a more cautious response, saying only that Russia "is ready to work with the Ukrainian side on a memorandum on a possible future peace accord," stopping short of agreeing to an immediate ceasefire. And his aide Yury Ushakov confirmed that a ceasefire timeframe was not "discussed."

Although Putin called the conversation "frank, informative and constructive" and thanked Trump for his diplomatic efforts, he signaled that Moscow's core demands remain unchanged. "I would like to note that, in general, Russia's position is clear. The main thing for us is to eliminate the root causes of this crisis," Putin said.

Meanwhile, Kremlin spokesman Dmitry Peskov said that if the United States can "help to achieve our goals through peaceful means, then this is indeed preferable."

Asked about the possibility of an in-person meeting between Trump and Putin, an idea the U.S. president floated on Friday, Peskov said that "it will largely depend on what they themselves decide." The timing and details of such a meeting "need to be worked out" by the two leaders, he added.

In response to the Putin-Trump call, Zelensky said Monday that he spoke to Trump twice, before and after the phone call. "I reaffirmed to President Trump that Ukraine is ready for a full and unconditional ceasefire," he said on X, highlighting that it is crucial "not to dilute this proposal."

"I also reiterated that Ukraine is ready for direct negotiations with Russia in any format that brings results," he said. "It is not necessary to convince Ukraine, and our representatives are prepared to make real decisions in negotiations."

He added that "it is crucial for all of us that the United States does not distance itself from the talks and the pursuit of peace," calling for further sanctions if Russia "refuses to stop the killings."

One day ahead of the Putin-Trump call, Russia launched what Ukraine said was its largest drone attack since the conflict began. After a night of air raid alerts, Ukraine's air force said Sunday morning that Russia had launched 273 drones at Ukrainian cities, surpassing the previous record set in February on the third anniversary of the war.

EUROPE'S REACTION?

Following the phone call, clear differences in the approach between Washington and Europe are emerging, the Frankfurter Rundschau, a German newspaper, said in a Tuesday article.

While Trump depicted Russia as an economic partner, Europe stressed the need to "increase pressure on the Russian side through sanctions," it said.

A day before the phone call, leaders from Britain, France, Germany and Italy said they spoke with Trump, urging "Putin to take peace talks seriously." French President Emmanuel Macron said on X that Putin must show his commitment to peace by accepting a 30-day unconditional ceasefire proposed by Trump and backed by Ukraine and Europe.

The leaders "also discussed the use of sanctions if Russia failed to engage seriously in a ceasefire and peace talks," the British government said in a statement.

According to Bloomberg, several European countries were "shocked" that Trump did not want to push Putin with sanctions, and have aired their disappointment after being briefed by Trump following his phone call with Putin.

European leaders agreed to step up sanctions pressure on Russia, German Chancellor Friedrich Merz said in an X post late on Monday, following Trump's briefing.

The EU approved a fresh package of sanctions on Russia on Wednesday, set to be adopted this week, including blacklisting some 200 oil tankers used to circumvent curbs on Russian oil exports as the bloc threatens further punishment if Moscow does not agree to a Ukraine ceasefire.

Ursula Schrode, professor of Political Science at the Institute for Peace Research and Security Policy, said in a recent interview that though details have not yet been announced, this will send a strong political signal of European unity, noting that the move is especially significant amid the bloc's growing fatigue and frustration towards Trump's stance on the negotiation process. "One of the greatest risks now is a complete U.S. withdrawal from the peace process, leaving the EU to bear full responsibility," she said.