Map of China on U.S. Military Badge Angers Beijing

Chinese state media has condemned the U.S, military after troops taking part in a simulated island assault exercise used a patch showing a military drone in front of a silhouette of China.

The drill was being conducted off the coast of California, but Chinese media said the use of the patch and the nature of the island drill indicated that troops were training for possible combat amid the archipelagos of the South China Sea.

Air Force magazine reported that the Air Force drill—named Exercise Agile Reaper—involved three MQ-9 Reaper drones attached to the U.S. Navy's Third Fleet, which is responsible for overseeing the eastern and northern Pacific Ocean.

The Reaper drones conducted air strikes on mock targets during an amphibious assault drill on San Clemente Island, some 60 miles off the California coast, Air Force reported.

The drones belonged to the 29th Attack Squadron, an Air Force unit based at Holloman Air Force Base in New Mexico. Commander Lieutenant Colonel Brian Davis told Air Force: "It's a demonstration of our capability to rapidly move the MQ-9 anywhere in the world, to unfamiliar locations, and then get out and show the operational reach capabilities of the MQ-9."

But Chinese state media saw the exercises as evidence of planned U.S. aggression in the South China Sea, which has become a hotspot in the simmering conflict between Washington, D.C. and Beijing. China claims control of most of the area, despite overlapping claims with its neighbors.

The sea is a busy shipping route and could be home to some 11 billion barrels of untapped oil and 190 trillion cubic feet of natural gas, as well as extensive fishing grounds.

Beijing has effectively taken control of the region by building a network of militarized man-made islands and expanding existing reefs and shoals. Some of these bases are able to host nuclear-capable bombers, fighter jets, warships and hypersonic missiles.

U.S. warships and aircraft have been conducting regular "freedom of navigation" operations in what Washington maintains are international waters in the South China Sea, much to Beijing's chagrin. Both accuse the other of risking conflict in the region.

The nationalist Global Times newspaper—owned by the People's Daily which is the official publication of the Chinese Communist Party—published an editorial on Tuesday condemning the California drone exercise.

"Washington is stepping up preparations for war against China, and this type of drone that has participated in murders and other attacks around the world will also play a role in it," the editorial said. "This is the strategic signal sent from the exercise.

"This is to stir hostilities between the two countries, and is also a blackmail to China," it said of the patch used by those participating. "Using such an armband with a Chinese map will stimulate people's imagination and create a picture of China and the United States going to war."

The editorial also warned that any U.S. action in the South China Sea would be met with a "fierce counterattack." It added: "If Washington wants to try its luck, the Chinese military and Chinese people will surely rise to the challenge and fight to the end."

Newsweek has reached out to the U.S. Air Force for comment.

US, China, patch, drone, South China Sea
This file photo shows an MQ-9 Reaper drone during a training mission at Creech Air Force Base on November 17, 2015 in Indian Springs, Nevada. Isaac Brekken/Getty Images/Getty