The RC-135S Cobra Ball is a MASINT aircraft designed to observe ballistic missile flights at long range.
The RC-135S was used primarily as a traditional mission in the past against Russia. It performed numerous aerial reconnaissance missions of national-level significance. The aircraft is equipped with special optical instruments. The RC-135S Cobra Ball is an extensively modified C-135. It tracks missile systems for treaty verifications and has a growing role in theater missile defense. Cobra Balls specialized employs sensitive telescopic monitoring device, advanced optics and infrared sensors, providing national and theater command authorities with intercontinental ballistic missile treaty verification data and Theater Air Defense warning.
There are four RC-135S in service and they are part of the 55th Wing, 45th Reconnaissance Squadron based at Offutt Air Force Base, Nebraska. The RC-135S was originally assigned to Shemya and was used for observation of ballistic missile tests on the Kamchatka peninsula in conjunction with Cobra Dane and Cobra Judy.