Russia and Ukraine are fighting the kind of drone war the US military has been worrying about, and it's scrambling to prepare for a future that's already here

• The scale of the drone war in Ukraine is one of the most striking features of the conflict.
• For the US military, widespread drone use isn't a surprise, but it does present new challenges.
• The Pentagon has several efforts underway to strengthen its drone defenses quickly.

The drones clouding the skies over Ukraine have been one of the most visible and innovative aspects of the 18-month conflict. A range of drones, from jury-rigged commercial models to purpose-built military aircraft, are now being used for a broad set of missions.