Updated

Thousands of Polish and NATO troops have launched major defensive exercises in Poland's north amid security concerns raised by war games recently held by neighboring Russia and Belarus.

The Dragon-17 exercise involves some 17,000 troops and some 3,500 units of equipment and runs through Sept. 29. For the first time the bi-annual drill is joined by Poland's new defense force, the Territorial Defense Forces, which train civilian volunteers to support the regular troops.

Deputy Defense Minister Michal Dworczyk is expected to visit the exercise on Thursday. He has said the drills test defensive operation between Polish troops and those deployed in Poland by NATO and by the U.S. in response to the region's concerns over Russia's military activity.

Russia and Belarus wrapped up joint weeklong war games on Wednesday.