The attack came as U.S. officials were expected to hold peace talks with Ukrainian and Russian officials in the coming days.

"We need to sit down and discuss this seriously," Putin told reporters at the end of a three-day visit to Kyrgyzstan. He described U.S. President Donald Trump's 28-point peace plan as "a set of issues put forward for discussion" rather than a draft agreement.

A Russian drone and missile strike on the Ukrainian capital Kyiv has killed at least one person and injured seven others, city officials say. Early on Saturday morning residential buildings in several districts were hit and loud explosions could be heard across the city.

Ukraine says it used sea drones to strike two oil tankers that are part of Russia’s sanctioned shadow fleet and were a few dozen kilometres off the coast of Turkey.

Certainly, the latest rounds of American bargaining and pressure on Ukraine are the most substantial yet. “This isn’t another round of what we saw before,” says a Western diplomat in Kyiv. Those close to the talks speak of “serious progress” bringing some Ukrainian and Russian positions together.

Ukraine’s chief negotiator, in an exclusive interview, says conceding sovereign territory is off-limits in peace talks.

The Kremlin pitched the White House on peace through business. To Europe’s dismay, the president and his envoy are on board.

Ukrainian naval drones hit two oil tankers from Russia's so-called "shadow fleet" as they travelled through the Black Sea, Ukrainian officials have said. Footage verified by the BBC shows waterborne drones speeding through the waves into the vessels, before detonating into a ball of flame, sending black smoke into the air.