An American spy plane made the closet-ever run on China's coastal defenses on Monday, coming within 25.33 nautical miles before turning back, according to researchers in Beijing.
The U.S. Air Force RC-135U Combat Sent was one of three American reconnaissance aircraft operating in the South China Sea, the South China Sea Strategic Situation Probing Initiative (SCSPI)—a Peking University think tank—said on Twitter.
Flight-tracking data illustrating the Boeing aircraft's route on Monday morning local time shows it having made a beeline through the Bashi Channel between southern Taiwan and the Philippine island of Luzon.
The RC-135U, which gathers intelligence on radar systems, then makes a sortie toward China's southeastern coastline between the provinces of Fujian and Guangdong before turning back.
The run took the U.S. spy plane within 25.33 nautical miles of China, according to Beijing-based SCSPI, which called it the "short distance" an American reconnaissance aircraft had reached the coastline, based on publicly available data.
However, it is unclear just how precise the public flight-tracking data is at measuring aircraft distances from the coastline.
SCSPI, which tracks U.S. military activity around the Chinese mainland, said the Combat Sent was using the transponder code AE01D5.
The aircraft was one of two other intelligence gathering planes operating in the South China Sea on Monday, along with a P-8 Poseidon and an EP-3, according to the research institute.
USAF RC-135U Combat Sent #AE01D5 just set a new record of 25.33NM, the shortest distance US reconnaissance aircraft have reached from the China's coastlines, based on public data so far.
— SCS Probing Initiative (@SCS_PI) March 22, 2021
In addition, there was also a P-8A & an EP-3E spotted over the #SouthChinaSea, March 22. pic.twitter.com/uLv49u70Gv
The U.S. Air Force RC-135U has found its way into Chinese media reports already several times this year. Earlier this month, state broadcaster CCTV had also tracked its reconnaissance missions into the Yellow Sea and East China Sea from Kadena Air Base in Okinawa, Japan.
Last week, SCSPI released its annual report into U.S. Navy and Air Force activity in the South China Sea in 2020. It concluded that American spy planes flew nearly 1,000 sorties into the contested waters last year.
U.S. heavy bombers and warships conducted a record number of missions around Chinese-controlled islands, the think tank said, exerting "maximum pressure" on China in the process.
Since 2009, the U.S. military has "significantly enhanced the frequency of activities in the region by boosting the presence of surface vessels by more than 60 percent, reaching about 1,000 ship-days a year," SCSPI told Newsweek last October.
"In the air, it sends on average three to five warplanes to the South China Sea per day, most of them being reconnaissance aircraft, making a total of more than 1,500 sorties a year, almost twice as many as in 2009," it continued.
The heavy U.S. presence in the seas around China come as the Chinese military steps up its own warfighting capabilities and conducts probing flights near Japan and Taiwan on a near daily basis.
Key U.S. allies have also taken part in freedom of navigation missions in the South China Sea. An Australian naval vessel was present last year, and German and British warships are expected to transit the waters in 2021.
