By Guy Faulconbridge and Max Hunder MOSCOW/KYIV (Reuters) -On the eve of peace talks, Ukraine and Russia sharply ramped up the war with one of the biggest drone battles of their conflict, a Russian highway bridge blown up over a passenger train and an ambitious attack on nuclear-capable bombers deep in Siberia.

According to Ukrainian security sources, a coordinated drone attack code-named “Spider’s Web” targeted four Russian airbases, including one in Siberia.