A planned summit between U.S. President Donald Trump and Russian President Vladimir Putin was put on hold on Tuesday, as Moscow's rejection of an immediate ceasefire in Ukraine cast a cloud over attempts at negotiations.

The Kremlin denied Tuesday that it was holding up President Donald Trump’s latest push to end the war in Ukraine, and insisted it had not changed its demands ahead of possible talks. Trump had announced that Russia and the United States' top diplomats would meet this week, with his own summit with Vladimir Putin to follow in Budapest, Hungary.

Russia's modified drones are piercing Ukraine's defences at greater rates than before, targeting energy infrastructure.

U.S. president wants a swift end to the conflict, but both sides are digging in over the region in Ukraine’s east.

As temperatures drop in Ukraine, Russia has stepped up drone attacks on power facilities supplying millions of homes across the country.

By Gram Slattery, John O'Donnell and Jonathan Landay WASHINGTON/FRANKFURT (Reuters) -Russia reiterated its previous terms for reaching a peace deal with Ukraine in a private communique sent to the U.S.

The 'massive' attack targeted a plant in the city of Bryansk that produces components used in Russian ammunition. It follows Donald Trump's decision to shelve a plan to meet Vladimir Putin in Budapest.