Reports say Russia has already begun rounding up men in occupied parts of southern and eastern Ukraine to compel them to fight their countrymen seven months into the Russian invasion in a widely anticipated move that Kyiv has warned is a breach of international law.

The Geneva Conventions forbid occupation forces from compelling the local population to enlist in the occupier's armed forces.

RFE/RL's Ukrainian Service quoted the Moscow-installed leader of annexed Crimea, Sergei Aksyonov, as saying on September 25 that his authorities had already delivered 1,200 troops to mainland Ukraine in response to Russian President Vladimir Putin's partial-mobilization order on September 21.

Aksyonov said on September 25 that "Crimea will finish the mobilization measures today by the end of the day, carrying them out in full," according to RFE/RL's Russian Service.

He had previously said mobilized Crimeans would be sent to Sevastopol "for retraining."

But on September 25, Aksyonov said 1,200 "volunteers" had been sent to mainland Ukraine and two more "battalions" were being prepared.

There are concerns that, as in parts of Russia, Moscow-backed authorities are pressing minorities and other vulnerable groups into military service.

Human rights activists said about 5,000 Crimean residents had already received summonses since Putin's call-up announcement on September 21.

Russian authorities reportedly this week forbid Crimeans from leaving the peninsula without the permission of the military authorities.

Ukrainian President Volodymyr Zelenskiy, who has vowed to fight until his country wins back "every centimeter" Russia has occupied, has said Kyiv has evidence that occupation authorities are targeting Crimeans to fight for Russia.

He has stressed that forced conscription by occupying armies of local populations contravenes international law.

Moscow incorporated Crimea into the Russian Federation in 2014, but a UN vote overwhelmingly rejected that annexation and supported Ukraine's territorial integrity.

Russia controls around one-fifth of Ukraine seven months into its full-scale invasion, including the Crimean Peninsula that it forcibly annexed in 2014. But a Ukrainian counteroffensive this month has retaken thousands of square kilometers, according to Kyiv.

This week, Russia and its separatist allies in eastern Ukraine organized what Kyiv dubbed "sham" referendums on September 23-27 in four areas where they control large swaths of territory: Donetsk and Luhansk in the east and Kherson and Zaporizhzhya in the southeast.

The New York Times on September 25 quoted witnesses and Ukrainian officials as saying all men between the ages of 18 and 35 have been forbidden to leave Russia-controlled territory around Kherson and Zaporizhzhya and ordered to report for military duty.

It quoted sources as saying many young men are in hiding or trying to escape.

The Geneva Conventions also prohibit the transfer of civilians from occupied regions into its own territory, a safeguard that Russia quickly abandoned in this conflict as it vetted and forcibly moved Ukrainians from the war zone into Russian territory by the tens of thousands with the use of "filtration" centers.