WASHINGTON/MOSCOW — United States President Donald Trump on Saturday played down prospects of a summit with Russian President Vladimir Putin anytime soon, even as a top Kremlin negotiator huddled for talks with US officials on ending the conflict in Ukraine.

"I'm going to have to know that we're going to make a deal. I'm not going to be wasting my time," Trump told reporters aboard Air Force One as he headed to Asia, days after plans for a summit with Putin in Budapest collapsed.

"I've always had a great relationship with Vladimir Putin, but this has been very disappointing," he said.

The remarks came as Kremlin negotiator Kirill Dmitriev met with Trump administration officials on Friday and Saturday, a Russian source familiar with the talks told Agence France-Presse. Talks were expected to continue on Sunday. US media reported that Dmitriev met with Trump's special envoy Steve Witkoff on Saturday in Florida.

Dmitriev told CNN on Friday that a diplomatic solution to the conflict in Ukraine was within reach, after Ukraine's President Volodymyr Zelensky said he backed Trump's proposal to make the current front line the basis for negotiations with Russia.

"I believe Russia and the US and Ukraine are actually quite close to a diplomatic solution," Dmitriev told CNN. "It's a big move by President Zelensky to already acknowledge that it's about battle lines. You know, his previous position was that Russia should leave completely, so actually, I think we are reasonably close to a diplomatic solution that can be worked out."

The Kremlin said on Sunday that it was wrong to talk about cancellation of a meeting between Putin and Trump, but added that preparation for it was needed, state television Vesti reported on Telegram.

"Presidents cannot meet for the sake of meeting, they cannot just waste their time, and they are open about that," Kremlin spokesman Dmitry Peskov told state TV Kremlin correspondent Pavel Zarubin. "That's why they instructed (Russian Foreign Minister Sergey) Lavrov and (US Secretary of State Marco) Rubio to prepare this process. The process is complicated."

On the ground, Russian missile and drone attacks on Ukraine overnight into Saturday killed at least four people and wounded 20, officials said.

In Russia, the Defense Ministry said its air defenses shot down 121 Ukrainian drones overnight.

Meanwhile, Putin announced on Sunday a successful final test of a new nuclear-powered cruise missile, the Burevestnik, praising the "unique" nuclear-capable weapon with a range of up to 14,000 kilometers.

Russia says the weapon is "invincible" to current and future missile defenses, with an almost unlimited range and unpredictable flight path.

Agencies via Xinhua