TAN TAN, Morocco (AP) — High-ranking military officials from the U.S. and its top African allies watched intently as dust and flames shot up from pieces of the Sahara Desert hit by tank and artillery fire. They looked up as pilots flew F-16s into formation. And they listened intently as Moroccan and American personnel explained how they would set up beachheads to defend the Atlantic coastline in the event of a potential invasion.

The practice scenario was among those discussed during Africa Lion, the United States’ largest annual joint military exercise on the continent, which concluded Friday in Morocco.

Over the past two weeks, roughly 8,100 military forces from nearly three dozen maneuvered throughout Tunisia, Ghana, Senegal and Morocco as part of the war games held this year as militaries confront new challenges in increasingly volatile regions.