Russian S-400 Missile System Deployments are Heating Up the Arctic 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. Here's What You Need to Remember: As the ice continues to melt at a faster pace, opening up new waterways for maritime transit and segmenting new areas of ice and land, Russia has sought to expand its territorial boundaries in the Arctic beyond the continental shelf northward from the boundaries specified in the United Nations Convention Law of the Sea. 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.