Ukrainian President Volodymyr Zelensky said on Tuesday that he had had a "productive" conversation with his U.S. counterpart, Donald Trump, on ending the war, sanctions on Russia and the finalisation of a U.S.-Ukraine drone deal.

"President Trump is fully informed about Russian strikes on Kyiv and other cities and communities," Zelensky wrote on X, referring to intensifying drone and missile attacks.

Trump, who has signalled frustration with Vladimir Putin in recent weeks, has given the Russian president until August 8 to make peace in Ukraine or face tougher sanctions.

A source in Washington said U.S. envoy Steve Witkoff would be meeting the Russian leadership in Moscow on Wednesday.

Speaking in his nightly video address, Zelensky said Trump "knows the situation along the front line," which extends for 1,000 km (620 miles) through eastern and southern Ukraine.

Ukraine, he said, had long supported U.S. proposals for an immediate ceasefire and had proposed a number of formats to implement a halt to the fighting.

"We have spoken with and proposed to Russia quiet in the skies, no missile and drone attacks and specifically no attacks on civilian infrastructure or on the energy sector," he said.

"All of this has been violated by the Russians and in a very cynical fashion."

Trump has threatened to hit Russia with new sanctions and impose 100% tariffs on countries that buy its oil, although sources close to the Kremlin have told Reuters that Putin is unlikely to bow to the ultimatum.

Zelensky said Ukraine was also ready to conclude a deal with the U.S. on the purchase of Ukrainian drones that would amount to "one of the strongest agreements". He had earlier said the deal was worth around $30 billion.

Ukraine is increasingly seeking financing and investment from its foreign partners to bolster its burgeoning domestic arms industry.

Zelensky said Kyiv's European partners had so far pledged to buy more than $1 billion in U.S. weapons for Ukraine as part of a new scheme.