Belarus said 30,000 Russian troops participating in joint drills would stay in the country indefinitely despite earlier pledges by Moscow that they would return to base.

Belarusian defence minister Viktor Khrenin on Sunday said Russian president Vladimir Putin and his Belarusian counterpart Alexander Lukashenko made the decision to extend the drills for an unspecified period because of “increasing military activity on [the countries’] eastern borders and the worsening situation in the Donbas” in eastern Ukraine.

The announcement came on the day the joint military exercises in Belarus were scheduled to end and will add to western fears that Russia is planning an invasion of Ukraine. Moscow has massed as many as 190,000 troops on the Ukraine border, including those participating in the drills in Belarus.