Of course they are. Citizens can be conscripted.

This is the best summary I could come up with:

Ukrainians living in Russian-occupied territory are being forced to assume Russian citizenship or face retaliation, including possible deportation or detention, a new US report has said.

Yale University researchers found that residents of the Luhansk, Donetsk, Kherson and Zaporizhzhia regions were being targeted by a systematic effort to strip them of Ukrainian identity.

Russian prime minister Mikhail Mishustin said in May that Moscow had given passports to almost 1.5 million people living in parts of Ukraine’s Donetsk, Luhansk, Zaporizhzhia and Kherson regions seized since October last year.

“This number has grown since then, with leaders of the so-called Luhansk People’s Republic (LPR) claiming that three-quarters of residents of that oblast [region] had received Russian citizenship,” the report said.

The report included a timeline of increasingly aggressive measures to pressure or force Ukrainians to become Russian citizens, starting in May 2014, when Russia illegally annexed Crimea.

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