The warring sides also exchanged prisoners in one of the few results of talks last week, and Russia reported new attacks on the front line.

Most of the drones and missiles were intercepted, according to the Ukrainian Air Force, and there were no immediate reports of widespread damage.

Ukraine’s shock drone strike on Russia’s strategic bomber fleet this week has generals and analysts taking a new look at threats to high-value United States aircraft at bases in the homeland and abroad – and the situation is worrisome.