Russia launched a barrage of drones and ballistic missiles across broad swaths of Ukraine early Friday, killing at least four people and injuring dozens of others, days after Kyiv launched a daring raid on Moscow’s fleet of strategic bombers.

Ukrainian strikes reportedly targeted Engels and Dyagilevo airfields — two key hubs for Russia's long-range bomber fleet, as well as logistics sites in Russia's Kursk Oblast.

Drones are “ubiquitous, because they are quite useful, and they're demonstrating that every day in Ukraine,” one analyst told NBC News.