A major U.S.-led military exercise with 18,000 soldiers from 19 primarily NATO countries has kicked off in the alliance's eastern flank involving Poland and the three Baltic states of Estonia, Latvia, Lithuania.

The U.S. Army Europe said Sunday the Saber Strike 18 drill is spread around the region until June 15 as "a demonstration of the commitment and solidarity of the Alliance" at the time when Russia's military maneuvers are increasingly worrying nearby NATO members.

It stressed, however, that Saber Strike "is not a provocation of Russia."

NATO has deployed some 6,000 troops in the Baltics and Poland.

Lithuania's defense ministry also announced the start of the country's largest-ever national drill, "Thunder Storm," with some 9,000 troops.

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Non-NATO member Israel will be taking part in Saber Strike for the first time. Several dozen Israeli paratroopers are being sent to Eastern Europe to take part in the exercise.

Until now it has been one huge exercise but this year it was decided to split it into two different scenarios; one scenario is a large exercise of 18,000 fighters from many countries, while the second, in which Israel will take part, will have a more limited number of troops. During the exercise the fighters will be trained in combat in several countries, contend with airstrikes by foreign forces, and cross bridges and rivers.

The other armed forces participating in the exercise are from United States, Britain, France, Italy, Canada, Latvia, Lithuania, the Netherlands, Macedonia, Poland, Spain, Romania, Norway, the Czech Republic, Romania and NATO.