US President Donald Trump confirmed that his Ukrainian counterpart Volodymyr Zelensky would visit Washington on Friday to sign an agreement on rare earth minerals, while the latter said the success of the deal would hinge on the talks that take place and continued US aid.

Under the deal, which Ukraine's Prime Minister Denys Shmyhal has called "preliminary", Kyiv would hand some revenue from its mineral resources to a fund jointly controlled by the US.

Trump said Zelensky would sign the agreement on rare earths and discuss other topics during his visit but suggested Washington would not make far-reaching security guarantees.

"I'm not going to make security guarantees beyond-very much. We're going to have Europe do that," Trump said, without elaborating.

Zelensky, speaking in his nightly video address, said his talks with Trump would stress the importance of obtaining security guarantees "to ensure that Russia no longer destroys the lives of other nations", and added that continued US aid was vital.

"For me and for all of us in the world, it is important that American aid is not halted. Strength is needed on the path to peace," he said.

Zelensky later told a news conference that he would immediately follow the trip with talks with British Prime Minister Keir Starmer and other European leaders in Britain over the weekend.

His comments about the deal and the US visit came as discussions were fraught over the minerals issue, which would grant the US preferential access to Ukrainian natural resources in exchange for US support.

Difficult work ahead

Officials late on Tuesday said they had come to an agreement following protracted negotiations, but Zelensky told reporters in Kyiv that more difficult work lay ahead.

Further discussions between US and Ukrainian officials would determine the nature of security guarantees for Ukraine and the exact sums of money at stake in the accords.

However, Trump earlier brushed aside Ukraine's aspirations of joining the Atlantic defense alliance, saying: "NATO — you can forget about it."

The Kremlin said on Wednesday that it was still waiting for official confirmation that the US and Ukraine had agreed on the terms of the minerals deal.

"So far, there are no official statements on this matter. We have only heard that Zelensky seemed to be going to Washington on Friday," Kremlin spokesman Dmitry Peskov said.

The Kremlin has also sought to approach Trump by encouraging US investments in natural resources in Ukrainian territory controlled by Russian forces.

Russian and US diplomats met in Istanbul on Thursday to discuss resolving bilateral disputes that are part of a wider dialogue the sides see as crucial to ending the military conflict.