Russia and Ukraine both launched record drone attacks on each other overnight, despite a phone call reported by The Washington Post from U.S. President-elect Donald Trump urging Russian leader Vladimir Putin not to escalate the conflict.

Trump's election to the White House has the potential to upend the almost three-year conflict and has thrown into question Washington's multibillion dollar support for Kyiv, crucial to its defense.

The Republican said on the campaign trail that he could end the fighting within hours and has indicated he will talk directly with Putin — a major break from the approach adopted by President Joe Biden.