The easternmost command center of NATO began being upgraded for quick reaction in the event of a threat to the alliance's eastern flank after Russia seized Crimea from Ukraine in 2014.
The Kremlin says Crimea, where Moscow is building up its military presence, is Russian land and its status non-negotiable.
German foreign minister says to review country's role in Afghanistan but spokesman states no big policy shift expected.
France, Germany, Italy and Spain are calling for a common European defense policy to match NATO's drive to beef up its own security forces in the wake of a major Russian build-up.
The combat deaths are rare for Western forces, who handed over the task of securing Afghanistan to local troops some two years ago.
U.S. looks to allies to fill battle groups of some 4,000 soldiers as part of NATO's response to Moscow's annexation of Crimea amid concerns it could try a similar tactic in ex-Soviet states.
'The concern is that the carrier group can be used as a platform for increased air strikes against civilians in Aleppo,' Secretary General Jens Stoltenberg says.
Exercise comes after Moscow complains about the deployment of NATO's forces near Russia's borders, promising to take countermeasures.
A U.S. intelligence official said on Friday that Russia had started moving the Iskander-Ms into Kaliningrad in what he said could be a gesture to express displeasure with NATO.
The case has the potential to further strain ties between the United States and Turkey, which is already demanding Washington hand over a U.S.-based Turkish cleric it alleges was responsible for the failed coup.