More than 2,000 troops of NATO's new spearhead force are training on their response to a crisis, using tanks and live munition at a test range in Zagan, in southwestern Poland.

The exercise Thursday is part of the alliance's massive maneuvers held on its eastern flank to reassure eastern members concerned over Russia's hostile actions in Ukraine.

The exercise, to test and refine the abilities of the Very High Readiness Joint Task Force, or spearhead, that was agreed on at last year's NATO summit, is being watched by NATO Secretary General Jens Stoltenberg, the supreme commander for Europe, Gen. Philip M. Breedlove, and defense ministers from Poland, the Netherlands, Norway and Germany.