Poland is planning to move around 10,000 troops to its eastern border with Belarus amid mounting concerns over Wagner forces in the region.

Wagner troops have been stationed within Belarus – a close ally of Russia – in the wake of a short-lived rebellion carried out by the group.

The Polish Defense Minister, Mariusz Blaszczak, told public radio that while 10,000 soldiers will be on the border, 4,000 will directly support the border guard and the remaining 6,000 will be in reserve.

Explaining the move, Blaszczak cited alleged violations of Polish air space by two military aircraft, accusations Belarus called “far-fetched.”

“The violation of Polish space by Belarusian helicopters cannot be underestimated because of the Belarusian approach,” Blaszczak said, calling it another provocation.

“Everything that is happening in Belarus is coordinated with the actions of Russian,” he said.

On Wednesday, Blaszczak agreed to send more troops to the border but did not detail an exact number, according to Polish state news agency PAP.

Meanwhile Russian Defense Minister Sergei Shoigu also discussed plans for Russia to build up its forces on its western borders, according to a readout from a board meeting published by the Defense Ministry on Wednesday.

Among the reasons for the move, Shoigu blamed increasing militarization in Poland.

Poland has been sounding the alarm about Wagner forces in Belarus in recent weeks.

The beginning of August saw increased activity near a thin strip of land between Poland and Lithuania, known as the Suwalki gap or corridor, which troops from the Russian mercenary group Wagner are moving toward in an apparent attempt to increase pressure on NATO and EU members.

Polish Prime Minister Mateusz Morawiecki recently warned that Wagner fighters could pose as migrants to try crossing the border.

Another of Belarus’s neighbors, Lithuania, has also shored up its border, citing the threat from Wagner fighters.