A ship-borne J-15 fighter jet prepares to land at the flight deck of the aircraft carrier Liaoning in 2018. (China military)

The US Indo-Pacific Command (USINDOPACOM) claimed on Thursday that a Chinese pilot earlier this month allegedly "performed an unsafe maneuver" while attempting to intercept a US aircraft belonging to the United States Air Force.

"On Dec. 21 (China Standard Time), a People’s Liberation Army - Navy J-11 fighter pilot performed an unsafe maneuver during an intercept of a US Air Force RC-135 aircraft, which was lawfully conducting routine operations over the South China Sea in international airspace. The PLAN pilot flew an unsafe maneuver by flying in front of and within 20 feet of the nose of the RC-135, forcing the RC-135 to take evasive maneuvers to avoid a collision," the command said in a statement.

The United States military claimed in a statement that the Chinese jet reached 20 feet from the US aircraft, forcing it to carry out a maneuver to evade a collision.

The incident happened on December 21 and included a Chinese Navy J-11 fighter aircraft and a U.S. air force RC-135 jet, the statement added.

China claims nearly all of the South China Sea and it has become one of many flashpoints in the relationship between it and the United States.

It is worth noting that US warships have passed through the South China Sea with increasing frequency in recent years, in a show of force against China.

On November 29, China's military announced it drove away a US guided-missile cruiser that intruded into waters near the South China Sea's "Spratly" Islands.

"The actions of the US military seriously violated China's sovereignty and security," then said Tian Junli, spokesman for the Southern Theatre Command of the People's Liberation Army.

The strategic term "international waters" has been used by the US and its allies several times to continue their provocations against China.