China is boosting its early warning and reconaissance abilities in the South China Sea, after several US warships and aircraft have deliberately trespassed into Chinese territorial waters and airspace.

A naval aviation division of the People’s Liberation Army Southern Theater Command recently wrapped up a long-duration AEW (Airborne Early Warning) training program which concluded in November, in which participating troops intercepted more than 10 kinds of simulated hostile anti-air radar signals and tested multiple tactics, the PLA Daily reported on Sunday.

Compared with the same training exercise that took place in 2018, this year’s training significantly extended the flight duration, set more intensive hostile activities and tactical backgrounds and focused more on nighttime training, the PLA Daily quoted Yan Liang, chief of staff of a regiment under the participating naval aviation division, as saying.

Unlike previous drills, the troops did not receive any training plan in advance, and entered the missions as if they were real, according to the report.

During the training, an aircraft group received urgent orders and shifted from training to a real combat state, as they were assigned an unexpected mission to track down and identify a group of maritime targets, the report said.

The Southern Theater Command Navy operates mainly in the South China Sea.

Training exercise like this will allow troops to become familiar with intense missions with early warning and reconnaissance aircraft and gain experience so they can commence missions in complicated, real situations, a military expert who asked for anonymity, told the Global Times on Sunday.

The US Navy has been frequently tasking warships into Chinese territorial waters in the South China Sea, and its Air Force has also been flying bombers, reconnaissance planes, drones and patrol aircraft in this area, but not publicizing it, US military newspaper Stars and Stripes reported on Wednesday.

Pacific Air Forces commander Gen. Charles Q. Brown noted the differing treatment during a recent teleconference from Hawaii.

“We’ve been flying in and around the South China Sea for really about the past 15 years, and I would probably tell you we’ve done some as recently as this week,” he told reporters on Dec. 6.

Last month, 7th Fleet announced that the guided-missile destroyer USS Wayne E. Meyer cruised past the Paracel Islands, a region subject to competing claims by China, Taiwan and Vietnam. The day before, the littoral combat ship USS Gabrielle Giffords steamed within 12 miles of Mischief Reef, a low-tide feature in the Spratly Islands.

There haven’t been recent announcements about military planes flying in the area. However, Brown said they happen on a regular basis and involve Air Force bombers, U-2 Dragon Lady reconnaissance planes and RQ-4 Global Hawk drones as well as Navy P-3 Orion and P-8 Poseidon maritime patrol aircraft.

“So, we have quite a bit of activity — air activity — within the South China Sea,” he said. “It doesn’t probably get as much press as what you hear about with the freedom of navigation and the maritime environment, but we do hear about it because we do get … calls from [China].”

Brown spoke to reporters, along with Air Force Chief of Staff Gen. David Goldfein, as the pair hosted a symposium involving leaders of air forces from various Pacific nations at PACAF headquarters on Joint Base Pearl Harbor-Hickam, Hawaii.

Goldfein told reporters the Air Force has maintained its presence in the Pacific, even as it has shrunk.

“We’re an Air Force that’s 300,000 less airmen and about 3,000 less aircraft than we were even back to 1991, and yet, if you look at our footprint and our posture in the Pacific, we haven’t changed. We’ve come down significantly in Europe. We’ve changed significantly in the United States. Our footprint in the Pacific has been very steady over time.”

Chinese naval early warning and recon aircraft will not only spot US vessels and aircraft and inform Chinese warships and fighter jets to expel them, but also record US electromagnetic signals, a move that will give the Chinese military an edge so it can launch targeted jamming or attacks if necessary, the expert said.

China is mass-producing special mission aircraft including anti-submarine aircraft, early warning aircraft, surveillance aircraft and electronic warfare aircraft, China Central Television reported last week.