Russia will take years to replace nuclear-capable bomber planes that were hit in Ukrainian drone strikes last weekend, according to Western military aviation experts, straining a modernisation programme that is already delayed.

The audacious attacks on Russian airfields highlight the power of unconventional, asymmetric warfare — and the threat to U.S. strategic bases and ports, experts say.

Russia and Ukraine have exchanged hundreds more prisoners as part of a major swap that amounted to a rare moment of cooperation in otherwise failed efforts to reach a ceasefire. The exchange