Why Did Russia Send More S-400 Missile Defense Systems to the Arctic? Moscow is beefing up its military presence in the Arctic and Washington is trying to respond in kind. Russia is adding more S-400 air defense systems to the Arctic in what can be seen as an overt effort to greatly “upgun” and further militarize its already sizable and growing Arctic footprint. Certainly the arrival of more S-400s in the highly contested and increasingly tense Arctic changes the tactical circumstances in which U.S. and allied aircraft can conduct operations, and it might not be a coincidence that these advanced Russian air-defenses are arriving shortly after Washington sent B-1 bombers to Norway for stepped up Arctic patrols.