(QHA) -

Russia has responded to the killing of five pro-Russian activists in Ukraine on Thursday by mounting military drills close to their joint border.

The Russian military held the drills in the Krasnodar region close to Ukraine, setting up a competition for jet fighter pilots.

Russian President Putin said it would be a “very serious crime” if Ukraine was using its army on its own people and threatened “consequences.”

“We are forced to react to such a development in the situation,”- Russian Defense Minister Sergei Shoigu said.

“Starting today, exercises of battalion tactical groups from the Southern and Western military districts will begin near the borders with Ukraine,”- he noted.

Ukraine’s Interior Ministry said pro-Russian militants had been killed by Ukrainian forces who were demolishing illegal checkpoints near the eastern city of Slavyansk.