Live Updates: Trump Visits U.A.E. in Last Stop of Middle East Tour

As of midday in Istanbul, neither side had said whether the Ukrainians and Russians would in fact meet. Russia’s Foreign Ministry said the talks had been postponed until the afternoon on Turkey’s request. Mr. Zelensky said Russia’s delegation “appears to be more theatrical than substantive.”

A Ukrainian official traveling with the country’s foreign minister in Turkey said Ukraine would only decide whether to meet the Russian delegation after Mr. Zelensky and President Recep Tayyip Erdogan of Turkey had lunch together on Thursday afternoon.

And overshadowing it all was President Trump, who told reporters traveling with him on Air Force One that “nothing’s going to happen until Putin and I get together.” Mr. Trump, who was in Qatar and the United Arab Emirates Thursday, had earlier said that he might travel to Turkey on Friday “if something happened” in the peace talks. However, there was no other indication that a last-minute summit would materialize.

“We have people right now negotiating,” Mr. Trump had said at an event with business leaders in Qatar.

Behind the brinkmanship were the two very different approaches from Moscow and Kyiv on how to end the war. Mr. Zelensky wants an immediate and unconditional cease-fire, followed by negotiations over a potential peace deal. But Mr. Putin, who appears confident of Russia’s upper hand on the battlefield, is refusing to stop fighting before he secures major concessions from Kyiv and the West.

Mr. Putin, in an apparent effort to show Mr. Trump that he is interested in peace despite Russia’s ongoing onslaught, first proposed talks between Russia and Ukraine last weekend. Mr. Zelensky upped the ante by promising to attend in person and calling on Mr. Putin to do the same. But when the Kremlin released its list of delegates for the talks Wednesday night, Mr. Putin’s name wasn’t on the list, and it remained unclear Thursday whether Mr. Zelensky or any Ukrainian officials would come to Istanbul to meet with the Russians.

“We need to understand the level of the Russian delegation and what mandate they have — whether they are even capable of making any decisions independently,” Mr. Zelensky said after landing in Ankara. “Because we all know who makes the decisions in Russia.”

Russian state media reported that the talks were supposed to take place at an Istanbul palace where Ukraine-Russia negotiations happened in March 2022. Dozens of reporters on Thursday morning thronged outside the side entrance to that palace, Dolmabahce, forcing confused commuters to scramble for a detour around the press scrum.

The Kremlin has been presenting Thursday’s proposed meeting as a continuation of the inconclusive 2022 talks, where Russia demanded that Ukraine pledge never to join NATO and to limit the size of its military.

Dmitri S. Peskov, Mr. Putin’s spokesman, told reporters that Russian negotiators in Istanbul had been waiting for Ukrainian officials since Thursday morning. He added that Mr. Putin was not planning to visit Turkey himself in the coming days, and that there were no immediate plans for a meeting with Mr. Trump.

As the drama played out, Secretary of State Marco Rubio said the Trump administration was “impatient” for progress in the peace talks between Ukraine and Russia.

Mr. Trump was “open to virtually any mechanism” that could engender a lasting peace, Mr. Rubio said, adding: “We remain committed to that.”

The Trump administration, he went on, was “obviously, like everyone else, impatient, we want to see it happen, but it’s difficult. But you know, hopefully progress will be made here soon.”

How did we get here?

The prospect of a high-profile cease-fire negotiation in Turkey was the latest turn in a rapidly shifting diplomatic landscape.

Mr. Trump came into office earlier this year promising to bring the war to a swift conclusion. He began his efforts on Feb. 12, with phone calls to Mr. Putin and to Mr. Zelensky, but did not coordinate with European allies, who have stood united behind Ukraine.

The Trump administration strategy was to pressure Kyiv, blaming Ukraine for being invaded by Russia.

“You should have never started it,” Mr. Trump said at one point, referring to Ukraine’s leaders. “You could have made a deal.”

In late February, Mr. Zelensky met with the American president in Washington, but the visit ended in disaster when Mr. Trump and Vice President JD Vance castigated the Ukrainian leader in the Oval Office for not being grateful enough for U.S. support. The Trump administration then briefly suspended military assistance and intelligence sharing.

At the same time, Mr. Trump was trying to induce Moscow to agree to a cease-fire by holding out the prospect of economic relief from sanctions.

With British and French guidance, Ukraine moved quickly to mend fences with the president and within less than two weeks, at a meeting in Jeddah, Saudi Arabia, agreed to a key demand of the Trump administration: an immediate and unconditional 30-day cease-fire, abandoning demands for security guarantees before a truce.

Mr. Putin rebuffed that idea. But both sides agreed to a limited truce covering strikes on energy infrastructure, although each accused the other almost immediately of violations.

Mr. Putin then proposed a three-day cease-fire to coincide with an annual Victory Day parade in Moscow commemorating the defeat of Nazi Germany in World War II. Kyiv did not agree to that.

Overall, during the first months of this year, while Mr. Trump was trying to broker peace talks, the hostilities were far deadlier than the same period last year, according to the United Nations.

On Saturday, one day after Mr. Putin’s Victory Day parade, the leaders of France, Germany, Britain and Poland traveled to Kyiv to issue an ultimatum: Russia either agreed to an immediate and unconditional cease-fire or it faced a new round of withering economic sanctions.

Mr. Putin responded with his own gambit: the proposal for Ukraine and Russia to resume direct negotiations starting on Thursday in Turkey.

Mr. Zelensky answered swiftly with his challenge to Mr. Putin to attend the talks.

What does Russia want?

When Mr. Putin and other Russian leaders talk about ending the war, they focus on what they call the “root causes” of the conflict — Kremlin shorthand for a range of issues including the existence of Ukraine as a fully independent and sovereign nation aligned with the West.

Specifically, the Kremlin says it wants control over five Ukrainian territories, including wide swaths of land it has failed to seize despite the years of war. Mr. Putin has also demanded that Ukraine agree to strict limitations on its military, and to not join NATO. He has also demanded a suspension of all Western military assistance to Ukraine before a cease-fire begins.

Despite the staggering losses his forces have suffered, Mr. Putin seems to believe he is in a strong position to make sweeping demands, gambling that his military will eventually bleed out the Ukrainians.

What does Ukraine want?

With Russia holding the initiative on the front for more than 16 months, many Ukrainians have concluded that they are unlikely to drive the Russians off their lands militarily. And so Kyiv wants to freeze the fighting where it is and then make a case that any formal recognition of Russia’s annexation of Ukrainian lands violate basic tenets of international law and set a dangerous precedent.

Kyiv has also said it will not accept any limitations on its military. Its European allies have vowed to continue to work to strengthen Ukraine after any truce to ensure Russia is not tempted to attack again.

There are also a host of other complicated issues at play, among them the return of thousands of children taken from their families to Russia.

Nataliia Novosolova contributed research. Nataliya Vasilyeva Qasim Nauman and Safak Timur contributed reporting.