The Ukrainian president's comments come after the Trump administration resumed sending some weapons to Ukraine, a week after the Pentagon had directed that some deliveries be paused, U.S. officials said on Wednesday.

ROME (Reuters) -Ukrainian President Volodymyr Zelenskiy said on Wednesday he had held a "substantive" conversation with U.S. President Donald Trump's Ukraine envoy, Keith Kellogg, in Rome shortly after Trump pledged to send more defensive weapons to Kyiv.

"While we are very optimistic about what Trump announced, it's cautious because he has yet to release the details. And because we don't know the details, we don't know what products are covered," O’Shaughnessy explained on Tuesday.