TAIPEI (Taiwan News) — A U.S. Air Force spy plane was detected by aircraft spotters flying over the edge of Taiwan's air defense identification zone (ADIZ) on Wednesday morning (Dec. 23).

At 8:15 a.m., aircraft spotter CANUK78 announced on Twitter that a USAF Boeing RC-135W Rivet Joint electronic surveillance aircraft with the registration number 62-4139 had been detected flying over the southern end of Taiwan's ADIZ. The aircraft appeared to be heading toward the South China Sea and was joined by a Boeing KC-135R Stratotanker.

At 8:38 a.m., aircraft monitoring enthusiast Golf9 also reported the presence of RC-135W and KC-135R. He speculated that the latter had refueled the former to the south of Taiwan, with the Stratotanker bound for the South China Sea.

Twitter user Ketagalan at 8:53 a.m. wrote that both the reconnaissance plane and tanker had flown through the Bashi Channel and had entered the South China Sea. Twitter user New 27 Brigade at 9:48 a.m. reported that the aircraft had passed through the Bashi Channel and had entered the waters off Taiwan's southwestern coast.

On Tuesday (Dec. 22), a People’s Liberation Army Air Force (PLAAF) Shaanxi Y-8 anti-submarine warfare plane and a Shaanxi Y-8 electronic warfare aircraft encroached on the southwest corner of Taiwan's ADIZ.

#USAF

Boeing RC-135W Rivet Joint (62-4139) heading towards the #SouthChinaSea with #PEARL69 (KC-135R Stratotanker) pic.twitter.com/CCAEmsy4fp

— CANUK78 (@is_keelu) December 23, 2020

#AE01D0 #62-4139 RC-135W#AE04C2 #59-1459 KC-135R

經巴士海峽進入南海 pic.twitter.com/Dgz5L5vaWH

— Ketagalan (@CCCDSLR) December 23, 2020