Russian and Ukrainian officials will meet in Istanbul to exchange their plans for how to end the three-year war, Europe's largest conflict since World War II, after Ukraine says it struck dozens of strategic bombers parked at airbases deep in Russia.

U.S. President Donald Trump has demanded Russia and Ukraine make peace, but so far they have not and the White House has repeatedly warned the United States will "walk away" from the war if the two sides are too stubborn to reach a peace deal.

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.