By Jessie Yeung, Ivana Kottasová and Svitlana Vlasova, CNN

(CNN) — Talks may take place between Russia and Ukraine in Turkey on Thursday. Ukraine’s President Volodymyr Zelensky said he would be there. US President Donald Trump also said he was open to going. The one man who has not said anything about going is Russian President Vladimir Putin.

The Kremlin has so far refused to say whether Putin – or anyone else – would travel to Turkey on Thursday even though it was the Russian leader who initially proposed the talks. Putin suggested the summit in response to the ceasefire-or-sanctions ultimatum given to Moscow by Ukraine’s European allies on Saturday.

Speaking to reporters on Tuesday, Kremlin spokesperson Dmitry Peskov said Putin would announce his decision in due course. “As soon as the president considers it necessary, we will announce it,” Peskov said.

Zelensky said he was ready to meet Putin in Turkey on Thursday, after Trump urged him to do so, but his office has made it clear he would not consider meeting anyone else if Putin decides against going.

“The president cannot meet with anyone else,” Ukrainian presidential aide Mykhaylo Podolyak told the Breakfast Show, a YouTube channel ran by Russian journalist Aleksandr Plyushchev.

“There is (one) person who makes decisions on behalf of Ukraine. Moreover, the US president has stated that he too can act as a key mediator, and accordingly there is a person in Russia who makes decisions. Only Putin can make decisions about continuing or stopping the war.”

Whether Trump will attend remains unclear. Top Trump administration officials plan to be in Turkey this week, but the president’s possible attendance remains an open question that will largely be dictated by whether his Russian counterpart attends, according to a senior administration official.

He is visiting the Gulf this week, making stops in Saudi Arabia, the United Arab Emirates and Qatar, for his first major overseas trip since the start of his second term. He said he could detour to Turkey “if I thought it would be helpful.”

“I think you may have a good result out of the Thursday meeting in Turkey between Russia and Ukraine,” Trump told reporters at the White House on Monday. “I don’t know where I’m going to be on Thursday, I’ve got so many meetings, but I was thinking about actually flying over there. There’s a possibility of it, I guess, if I think things can happen.”

Shortly after, Ukrainian President Volodymyr Zelensky said his country “would appreciate” Trump’s attendance, and said he supported Trump’s call for direct talks between himself and Russian President Vladimir Putin.

“It is important that President Trump fully supports the meeting, and we would like him to find the opportunity to be in Turkey,” Zelensky said in his evening address.

Direct talks between the leaders of Russia and Ukraine have not happened since the early weeks of Moscow’s unprovoked full-scale invasion in 2022.

Last weekend, Ukraine’s major European allies had given Russia an ultimatum: agree to an unconditional 30-day ceasefire in Ukraine or face “massive” new sanctions. They insisted there could be no new talks before a ceasefire.

Trump had supported the initiative, Germany’s new chancellor Friedrich Merz said. Trump had called earlier that week for a 30-day unconditional ceasefire in Ukraine, without providing a deadline. “If the ceasefire is not respected, the US and its partners will impose further sanctions,” he warned.

Dramatic change in approach

For months, Ukraine and its allies tried to convince the Trump administration that Putin acts in bad faith, and have said Russia’s agreeing to a ceasefire could function as a test of whether it is serious about achieving the peace the US president has long demanded.

In urging Zelensky meet Putin, Trump dropped his demand for Russia to agree to a ceasefire, marking a dramatic change in approach.

On Monday, the Kremlin said Putin was serious about trying to find peace through talks, but the spokesperson said he could not say more, according to Reuters news agency.

Russian Foreign Minister Sergei Lavrov spoke by telephone with his Turkish counterpart Hakan Fidan about Putin’s proposed talks with Ukraine, but a brief Russian foreign ministry account gave no indication whether Putin would attend, according to Reuters.

Zelensky said Monday that Moscow had been “silent” regarding Putin’s proposal to meet.

“Ukraine always supports diplomacy. I am ready to be in Turkey. Unfortunately, the world still has not received a clear answer from Russia regarding numerous proposals for a ceasefire,” Zelensky said in his evening address.

Zelensky said he had spoken to Turkish President Recep Tayyip Erdogan who “expressed full readiness to host the meeting.” The Kremlin said Putin spoke with Erdogan on Sunday, who “fully supported” Putin’s proposal for peace talks and had offered Istanbul as a venue.

“A new window of opportunity has opened with the recent contacts. We hope that this opportunity will not be wasted,” Erdogan said Monday, following his call with Zelensky.

The Trump administration has been growing increasingly frustrated that efforts to broker a peace deal between Russia and Ukraine have so far fallen short.

Last month, US Secretary of State Marco Rubio said that if there was no progress on Ukraine, the US would “need to move on.”