Last week, Ukrainian officials said, the partisans had a hand in a successful strike on a Russian air base, also in Crimea, which Moscow annexed eight years ago. It destroyed eight fighter jets.

“The goal is to show the occupiers that they are not at home, that they should not settle in, that they should not sleep comfortably,” said one guerrilla fighter, who spoke on condition that, for security reasons, he only be identified by his code name, Svarog, after a pagan Slavic god of fire.