The USAF has confirmed that the Chinese balloon was tracked by at least two U-2 Dragon Lady reconnaissance aircraft. The aircraft tracking sites and the balloon's position also confirm that a very rare and highly secretive RC-135U Combat Sent electronic reconnaissance aircraft was deployed in the balloon's path.

A Chinese balloon
On 2 February, Canada and the United States formally confirmed that a stratospheric balloon was flying over US territory (see related article). This announcement was not a surprise, as the balloon had in fact been followed for two days by the armed forces of both countries. China later formally identified the balloon as one of its own and used for meteorological purposes. The United States had already announced the identity of the balloon but disputed its use: it was a spy balloon.

U-2s out and about
Since its first flight in 1956, the U-2 Dragon Lady spy plane has been flying for the US Air Force (USAF). In addition to having been continuously modernised to the U-2S standard, this aircraft has also seen its capabilities develop: it is fully modular and can therefore cover a wide range of functions (optical and electronic reconnaissance, etc.).

In addition to its reconnaissance capabilities, it is also one of the few USAF aircraft capable of flying at very high altitudes; the USAF officially states that the U-2S can fly at an altitude of more than 70,000 feet (or more than 21,212 metres), thanks in part to its engine and long wings. The balloon in question was flying at an estimated altitude of 60,000 feet (18,300 metres), well above the maximum altitude of many aircraft. By comparison, the F-22 Raptor fighter jet could fly at an altitude of more than 50,000 feet (15,000 metres).

Splash one
On 5 February, the Chinese balloon was over the Atlantic, not far from the US coast of North Carolina. An F-22 then fired an AIM-9X Sidewinder short-range air-to-air missile, destroying the balloon. The balloon then descended rapidly before "crashing" into the sea. Air and sea traffic was halted throughout the area: in addition to ensuring safety, this measure also allowed the recovery of the balloon's components by several US Navy and Coast Guard vessels.

In addition to destroying the balloon, this event was also the first offensive firing of an F-22. For the occasion, the call sign used by the Raptor, FRANK01, was a reference to Frank Luke. This American pilot of the First World War is known in the United States for having destroyed, in only 17 days, a total of 14 German observation balloons, receiving in passing the nickname "Arizon Balloon Buster". He died in aerial combat on 29 September 1918 and was posthumously awarded the Medal of Honour, the highest American military honour.

However, the USAF did not specify what equipment the Dragon Lady carried: were they only used to track the balloon at an altitude where the balloon can fly or did they also use their flights to try to gather information about the balloon?

Strategic electronic reconnaissance
It is certain that the two U-2S were not the only aircraft involved in tracking the Chinese balloon: tankers, fighters (especially the F-22), AEW&C, etc. However, the USAF did not mention the presence of other electronic reconnaissance aircraft. However, by looking at the various sites tracking aircraft in flight, it was possible to see an RC-135U Combat Sent electronic reconnaissance aircraft (see images below).

The aircraft took off from Offutt Air Force Base (Nebraska, United States) at around 9 pm (Paris time) on 3 February. It then flew over the cities of St Louis (Missouri) and Nashville (Tennessee), both of which were overflown at the time by the Chinese balloon. After a flight of 7.5 hours, the Combat Sent landed at 8.29 a.m. (Paris time) at its base in Offutt.

At present, only two RC-135Us are in service with the US Air Force. In addition to being a rare aircraft, it is used for strategic purposes only, to provide information to the President of the United States, the Secretary of Defense, the Joint Chiefs of Staff and theatre commanders. Like most of the Offutt Base reconnaissance fleet, the RC-135U is a classified aircraft. The only technical information available is that the aircraft is in any case capable of locating, analysing and identifying radar emissions (naval, air or ground).