A Romanian soldier secures the perimeter around Romanian Air Force F16 fighter jets parked on the runway of the Air Base 86, in Borcea, southern Romania, Friday, Oct. 7, 2016. The air force staged an event to mark the entry into service of the first six US made aircraft, purchased from Portugal's military, as part of the process to replace the country's Russian made MIG 21 fleet.

NATO Buildup On Russian Border Largest Since Cold War

The United States’ envoy to NATO, Douglas Lute, told reporters that NATO and the US military may consider Russia a threat if they had nuclear weapons within range of NATO’s deployment.