France is planning its largest-ever military exercise involving 12,000 troops, including NATO allies, in the first half of next year, a chief of staff commander said on Tuesday.

The scenario envisages a major conflict with an unspecified foreign state, said Yves Metayer, commander of the troop deployment department at the French chiefs of staff.

The exercise takes place against the background of the Russian war in Ukraine, which began in February this year.

“The geopolitical context justifies this exercise,” Metayer said, but adding that the war game plan has been in the works since 2020 and is a follow-up to a French strategic review published in 2017.

The review pointed to “the need to prepare for a major conflict” after two decades of mostly asymmetric warfare involving non-state actors such as jihadists, he said.

“After the fall of the Berlin Wall, we allowed the mobilization mechanisms we had during the Cold War to decay,” he added.

The war games, dubbed Orion, will involve European NATO allies Germany, Britain, Belgium, Italy and Spain, as well as the United States.

Between late February and early May, 7,000 troops will play out a sequence that includes naval operations in the Mediterranean and an amphibious and airlift operation in southern France.

This phase will simulate an intervention in a country undermined by militia activity and neighboring a powerful nuclear state that is fomenting unrest.

From mid-April to early May, the soldiers will simulate an air and land conflict with the powerful state, with up to 12,000 soldiers stationed in northern France.

Orion will include land, sea, air and space components, including cyber warfare, as well as wartime civilian operations such as health services and transport, Metayer.