The Kremlin has justified its move into Crimea by saying ethnic Russians here are in danger of being attacked by Ukrainian fascists, and need to be saved by Moscow.

Yet the alleged threat to ethnic Russians, dominant in Crimea here for years, is hard to find. By contrast, a handful of local pro-Ukrainian activists are hounded and harassed by camouflage-wearing men roaming the streets.

On Thursday, as one impromptu patrol passed, a front door opened and Vasily Ovcharuk stepped out, looking left, then right. His face features prominently on fliers dropped into residents’ mailboxes, glued to a fence, and left at his door.

“Unfortunately, our neighbor betrayed Crimea’s interests,” it reads. “When we see him, let’s tell him he’s a traitor and ask him to get lost.”

Mr. Ovcharuk, 62 years old, has a head full of gray hair. One of his alleged crimes is speaking up for Ukrainian-language rights in Crimea. Back in January, Cossacks prevented him from laying flowers at the monument of Taras Shevchenko, Ukraine’s revered national poet.