A huge, Russian-led military exercise will take place over the next seven days, bringing together the six members of the Collective Security Treaty Organization (CSTO), the post-Soviet bloc equivalent to NATO. The exercise, which started Thursday in Tajikistan, comes amid a flurry of U.S.-led NATO exercises that have sprung up across Europe over the past six months and are designed to stem recent Russian hostility directed at European countries.

According to the CSTO, hundreds of Russian paratroopers parachuted in near the Tajikistan capital of Dushanbe and will commence a 200-mile march to the exercise area.

"Special mobile groups on quadricycles and motorcycles, as well as BMD-2KU and BTR-D combat4 vehicles and self-propelled artillery pieces and their crews disembarked from transport planes on the ground," the Defense Ministry said.

Troops from Armenia, Belarus, Kazakhstan, Kyrgystan, Tajikistan and Russia will take part in drills.

The exercise by former Soviet states comes during a time of strained relations between Russia and Europe over Moscow’s annexation of Crimea in March 2014 and the country’s continued involvement in the Ukraine war, which began in April 2014.

Recent diplomatic efforts from German Chancellor Angela Merkel and U.S. Secretary of State John Kerry to enforce the Minsk II agreement ceasefire, which went into effect on Feb. 15 this year, have have had little effect on the battlefield in the contested region of Donbas.

Intense fighting over the past six weeks, and the recent use of deadly Grad rockets, has eroded any semblance of peace that existed over the past three months. 

Meanwhile, the group charged with overseeing the ceasefire, the Organization for Security and Co-operation in Europe, reported on Wednesday that banned heavy weapons had gone missing from a secure storage unit in Donetsk. While it’s not known where the weapons are, they could be used in an expected military front that Ukrainian military chiefs and U.S. Secretary of Defense Ashton Carter predicted last week.