"You don't have the cards," President Trump dismissively told Ukrainian President Volodymyr Zelensky during their Oval Office blow-up in February. Three months later, Zelensky played a hand no one saw coming.

Assaults in Russia and Ukraine have shown major military powers that they are unprepared for evolving forms of warfare, and need to adapt.

Ukraine said it had used 117 drones to target airfields deep in Russian territory. The daring attack demonstrated low-cost precision strikes accessible to almost any state or militant group.