The Kremlin has denied media reports that Donald Trump held a call with Vladimir Putin, in which the US president-elect was said to have warned the Russian president against escalating the war in Ukraine.
The call, which was first reported by the Washington Post on Sunday, is said to have happened on Thursday.
Trump is also reported to have mentioned America's "sizeable military presence in Europe" to Putin.
When asked for confirmation of the call, Trump's communications director Steven Cheung told the BBC: "We do not comment on private calls between President Trump and other world leaders."
But he said leaders have begun the process of contacting the president-elect.
Russia's denial comes days after Russia and Ukraine launched their largest drone attacks since the start of the war.
Russia's defence ministry said it intercepted 84 Ukrainian drones over six regions, including some approaching Moscow, which forced flights to be diverted from three of the capital's major airports.
Ukraine's air force said Russia launched 145 drones towards every part of the country on Saturday night, with most shot down.
On Monday, at least six people were killed and 21 others injured in Ukraine following the latest series of air strikes by Russia.
Five were killed in the southern city of Mykolaiv and another was killed in Zaporizhzhia, authorities said. Volodymyr Zelensky, Ukraine's president, said that at least seven people including two children were hurt when an block of flats was hit by a missile in Kryvyi Rih, his home city in central Ukraine.
Russia, meanwhile, said it had destroyed 13 Ukrainian drones near the western regions of Kursk and Belgorod. It reported no deaths.
"Every day, every night, Russia unleashes the same terror," Zelensky wrote on Twitter following Monday's strike.
"More and more civilian sites are being targeted. Russia only wants to continue the war, and each of its strikes negates any claims of diplomacy from Russia."
Zelensky asked for "stronger global support" and more weapons to stop Russian aggression.
Trump has promised to end the conflict but has yet to outline how he intends to do so.
He has spoken to Zelensky since his election victory last week. A source told the BBC that the conversation lasted "about half an hour".
Zelensky has previously warned against conceding land to Russia and has said that without US aid, Ukraine would lose the war.
While Kremlin spokesman Dmitry Peskov on Sunday spoke to Russian state media of "positive" signals from the incoming US administration, others believe the returning president will not abandon Ukraine.
They include John Healey, the British defence secretary, who said he expected the US "to remain alongside allies like the UK, standing with Ukraine for as long as it takes to prevail over Putin's invasion".
Meanwhile, reports of Russian advances in Ukraine continue. Moscow's defence ministry said on Monday that its forces had captured the village of Kolisnykivka in the Kharkiv region.
Russian territorial gains in October were the largest since March 2022, according to analysis of Institute for the Study of War data by the AFP news agency.
