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.

The covert operation was described as one for the “history books” by Ukraine’s president. According to Ukrainian officials, nearly a third of Moscow’s strategic bomber fleet was destroyed or damaged with cheaply made drones sneaked into Russian territory in the span of a few hours on Sunday.

President Trump said Russian President Vladimir Putin told him he would have to respond to Ukraine’s recent attack, dampening the prospects for immediate peace between Moscow and Kyiv.