The United States has ramped up its aerial reconnaissance of the Chinese coast and the South China Sea to record levels, according to a Beijing-based think tank. In the past week alone, US air force E-8C surveillance planes were spotted closer than 100 nautical miles to the southeast coast of Guangdong province on four separate occasions, the South China Sea Strategic Situation Probing Initiative (SCSPI) said. On Thursday, the think tank released a scratchy audio recording of what appeared to be a warning from the Chinese navy to a US military plane to change course or be intercepted. SCSPI said the audio had been captured by a radio amateur that morning. US, China may ‘stumble’ into conflict in South China Sea It remains unclear which aircraft was involved but it was said to be flying close to the southern Chinese coast, north of the Taiwan Strait. It is unknown whether any subsequent aerial encounter took place. “At the moment the US military is sending three to five reconnaissance aircraft each day to the South China Sea,” SCSPI said. “In the first half of 2020 – with much higher frequency, closer distance and more variety of missions – the US aerial reconnaissance in the South China Sea has entered a new phase.” US planes have ventured “unusually close” to Chinese airspace several times since April, the think tank said. The closest flight to date was in May when a US navy P-8A Poseidon – designed for anti-submarine warfare – almost reached the 12 nautical mile limit near Hainan Island, on China’s southernmost tip. SCSPI said its statistics showed flights by US planes to about 50 to 60 nautical miles off the mainland were “frequent”. A record of 50 sorties – flying from nearby US land bases to the South China Sea – was set in the first three weeks of July, coinciding with separate Chinese and US military exercises in the area. On peak days, SCSPI said it had counted as many as eight US aircraft, including types P-8A EP-3E, RC-135W and KC-135. One such peak occurred on July 3, as aircraft carriers USS Ronald Reagan and USS Nimitz, along with their respective strike groups, entered the region. The two strike groups drilled twice – on July 4 and July 17. In between the exercises, the US State Department issued a statement describing China’s claim to the disputed waterway as “ unlawful ”. It added that Washington stood with the other Southeast Asian claimants. The resource-rich South China Sea is one of the world’s busiest waterways, with around a third of international shipping passing through it. China claims most of the area while Vietnam, the Philippines, Malaysia, Brunei and Indonesia all have overlapping claims. The range of US military planes involved in the South China Sea missions was an indication of their purpose, according to SCSPI director Hu Bo. These included anti-submarine patrol, communication signal collection, and radar frequency detection, among others. With the People’s Liberation Army also exercising in the Paracel Islands earlier this month, the US intelligence aircraft were probably collecting data on the PLA electronics, Hu said. “The increasing US military operations have become the largest risk and potential source of conflicts.” These operations have led to a number of incidents, and occasionally crises, in the past. The most serious occurred in April 2001 when a US navy EP-3E Aries II flew to within 59 nautical miles of Hainan Island and collided with an intercepting PLA navy J-8II fighter. The Chinese pilot died and the US plane was forced to land on Hainan, giving then-president George W. Bush the first diplomatic crisis of his tenure. In 2014, 2015 and 2017, the Pentagon repeatedly accused Chinese fighters of nearly causing accidents by making “unsafe” interception manoeuvres with US spy planes near the Chinese coast in the South China Sea, East China Sea and the Yellow Sea. How a mid-air collision in 2001 spurred China’s military modernisation Hong Kong-based military commentator Song Zhongping said the PLA could be expected to send fighters out to intercept and expel US aircraft on every close reconnaissance mission. “The PLA has developed a standard operating protocol on these US planes approaching Chinese airspace. With more frequent US provocations, the PLA will have more frequent interceptions too,” he said. “It poses a challenge to pilots’ skills and training, but the PLA has also become quite proficient to avoid possible accidents or collisions.”