Among the guests invited to observe the North Atlantic Treaty Organization’s biggest military exercise in more than a decade will be the alliance’s once, and potentially future, adversary: the Russians.

At first blush it might seem odd that the country which a rising number of NATO members view as the world’s gravest security threat would be given a ring-side seat to watch the alliance test its newly revamped response force.

Observing the exercise could give Russian military officials a chance to evaluate potential weaknesses of the NATO Response Force, which will be at the center of the sprawling air-land-and sea exercise which will take place in Spain, Portugal and Italy over more than a month beginning in October.

NATO’s European members are legally bound to invite Russia to observe, but there is a more practical reason to invite them as well, officials said.

“They will watch us anyhow, invited or not,” said German Army Gen. Hans-Lothar Domrose, commander of the Allied Joint Force Command at Brunssom, Netherlands.

Gen. Domrose noted that Russia aircraft have been flying over NATO exercises and Russian ships have been following allied operations.

Image: NATO ships in the Black Sea, Sept, 18, 2014 (photo: Sgt Matthew McGregor/Canadian Forces)