Upheaval in the positive atmosphere surrounding the planned Trump-Putin summit in Budapest, as the US president temporarily suspended preparations, estimating that Russia and Ukraine are not yet ready for meaningful peace talks.

According to a senior White House official who spoke to NBC News, after Donald Trump was briefed on the “productive” telephone conversation between US Secretary of State Marco Rubio and his Russian counterpart Sergei Lavrov, the US president judged that neither side in the Russia-Ukraine conflict is yet ready for serious peace talks.

“Rubio and Lavrov had a productive communication, so there is no need for an additional face-to-face meeting, and there are no plans for President Trump to meet with President Putin in the immediate future,” a second White House official said.

A source familiar with the talks said a further phone call between Rubio and Lavrov is expected within the week, without ruling out a future meeting. The two ministers will attend the Association of Southeast Asian Nations (ASEAN) Summit at the weekend.

Earlier, the Kremlin denied it was delaying Trump’s initiatives to end the war in Ukraine, stressing that it has not changed its positions ahead of possible negotiations.

Trump had announced that the foreign ministers of Russia and the US would meet this week, with his own summit with Putin to follow in Budapest. Russian officials, however, said no date has been set for either meeting.

“We cannot postpone something that has not been agreed,” Deputy Foreign Minister Sergei Ryabkov told Russia’s TASS news agency, responding to a CNN report that the Rubio-Lavrov meeting had been “frozen indefinitely.”

Ryabkov added that there has been no clear agreement on when or where the meeting could take place.

After a phone call with Vladimir Putin and a meeting in Washington with Volodymyr Zelensky, Donald Trump said he supports an immediate cessation of hostilities, as demanded by Kiev and its European allies.

“For now, both sides need to stop on the front lines, go home, stop fighting, stop killing people,” he told reporters from Air Force One. “They can negotiate something later,” he added.

On Tuesday, the leaders of Britain, France, Germany, Ukraine and the EU issued a joint statement backing Trump’s efforts to end the war, but stressing that Russia shows no intention of moving forward with a peace deal at this stage.

“We fully support President Trump’s position that the fighting must stop immediately and that the current line of contact must be a starting point for negotiations,” the British government said in a statement.

“We must step up the pressure on Russia’s economy and defense industry until Putin is ready to make peace,” the text added.

In an interview on NBC’s “Meet the Press” taped Friday, Zelensky called on Trump to toughen his stance on Putin, saying he was ready to attend the Budapest summit.