NATO launched its biggest military exercise in 13 years, mobilizing 36,000 soldiers, sailors and airmen from more than 30 countries, including, along with NATO allies, Austria and Sweden. Trident Juncture 2015 aimed to test the alliance's ability to respond to new security threats is hosted by Italy, Spain and Portugal at 16 different locations. More than 140 aircraft and about 90 ships will take part in this key exercise. The start of the drills - in this photo gallery by TASS.