(Same plane seen in flight here.
The RC-135S Cobra Ball is a United States Air Force reconnaissance aircraft equipped with special optical instruments designed to observe ballistic missile flights at long range. The aircraft is an extensively modified C-135 Stratolifter. There are two aircraft in service and they are part of the 55th Wing, 45th Reconnaissance Squadron based at Offutt Air Force Base, Nebraska. Cobra Ball aircraft were originally assigned to Shemya, Alaska and used to observe ballistic missile tests on the Kamchatka peninsula in conjunction with Cobra Dane and Cobra Judy.