Some 5,500 troops from the United States and European allies carried out a mock liberation of a fictional city in a large-scale military exercise Monday.

The maneuver in southern Germany was part of Exercise Saber Junction, an annual event led by the U.S. Army Europe.

It took place against the backdrop of tensions with Russia over its involvement in the conflict in eastern Ukraine.

U.S. Army Commander Lieutenant General Frederick B. Hodges said the exercise reflected NATO's resolve to demonstrate it can deter "Russian aggression" should one of its members ever be attacked.

Bosnia, Serbia, and Sweden participated in the exercise alongside troops from 13 NATO member states.