Sept. 14 (UPI) -- Russia launched its week-long military exercises in Belarus on Thursday, with nearly 13,000 troops massing near the borders of several NATO countries.
The Atlantic alliance is concerned the triennial exercises could be a rehearsal for real military action, or a ruse of war. Last conducted in 2014, the "Zapad," or "western" exercises, were followed months later by a war in Ukraine's eastern provinces.
The new military drills have alarmed officials across Western Europe. Although planned years in advance, the games come at a time of a Russian arms buildup and deteriorating relations between Moscow and the United States.
NATO believes the troop strength of Russian and Belorusian troops is considerably higher -- as military personnel and hundreds of tanks, aircraft and warships are also involved in the exercise, which span Russia and Belarus.
As part of the exercise, war games will be conducted along the borders of Finland, Estonia, Latvia, Lithuania and Poland. All except Finland are members of NATO.
Ukrainian President Petro Poroshenko -- concerned that the Zapad exercises could be the start of an invasion of Ukraine -- ordered increased security at the Russia-Ukraine border.
NATO has also stepped up its security, deploying 4,300 troops to Poland, Estonia, Latvia and Lithuania, and has increased flyover policing in those countries.
Thursday, Russian Defense Minister Alexander Fomin said the exercises are not indicative of any planned military action.
"I can calm our dear neighbors straight away," he said. "The exercise is absolutely peaceful and absolutely defensive in nature. In this case, the 'west' isn't to be taken in the broad, political sense of the geographic term as the countries of the West, of the European Union or the members of NATO."
Planners in Belarus, a former Soviet country, say the war games involve a fictional scenario in which terrorist attacks are launched by three unidentified countries in an attempt to destabilize Belarus as Russia sends in troops, weapons and funding. Russian tanks began traveling to Belarus on Wednesday.