Reported strikes on four airbases in Siberia mark escalation in cross-border incursions before Monday’s planned peace talks in Istanbul

Ukraine has launched a “large-scale” drone attack against Russian military bombers in Siberia, striking more than 40 warplanes thousands of kilometres from its own territory, a security official said.

The claims could not be independently verified. But if confirmed, the attacks would mark Ukraine’s most damaging drone strike of the war to date, amid an escalation in cross-border incursions before planned peace talks in Istanbul on Monday.