The United States conducts exercises in the South China Sea amid concerns with China.

BEIJING, (AP) – The US Navy and Marine Corps are conducting joint drills in the South China Sea, amid rising tensions with Beijing following the downing of a suspected Chinese spy balloon.

The USS Nimitz aircraft carrier strike group and the 13th Marine Expeditionary Unit have been performing “integrated expeditionary strike force operations” in the South China Sea, according to the 7th Fleet in Japan.

It stated drills involving ships, land troops, and aircraft took place on Saturday but didn’t say when they started or when they concluded.

China claims practically the whole South China Sea and actively opposes military operations by other countries in the contentious waterway, which transports $5 trillion in commerce each year.

The United States does not have an official stance on sovereignty in the South China Sea, but believes that freedom of navigation and overflight must be safeguarded. It sends ships sailing past reinforced Chinese outposts in the Spratly Islands many times a year, eliciting concerns from Beijing.

The United States has also strengthened its defence relationship with the Philippines, which has faced Chinese coast guard and ostensibly civilian but government-backed naval encroachment on islands and fisheries.

The military drills in the United States were arranged in advance. They come as already strained ties between Washington and Beijing have been compounded by a diplomatic spat started by the balloon, which was shot down in US airspace off the coast of South Carolina last weekend.

The unmanned balloon was geared to detect and gather intelligence signals, according to the US, while Beijing claims it was a meteorological research airship that had accidentally blown off course.

The balloon caused Secretary of State Antony Blinken to abandon an important trip to Beijing aimed at defusing tensions.

After first expressing sadness over the balloon, China has stiffened its stance, calling the US shootdown an overreaction and a breach of international rules. China’s military minister declined a phone call from US Defense Secretary Lloyd Austin to address the situation.

As part of its reaction to the event, the US has banned six Chinese firms it believes are tied to Beijing’s aerospace activities. The House also unanimously condemned China for a “brazen infringement” of US sovereignty and attempts to “deceive the world community via deceptive assertions about its intelligence gathering programmes.”

According to the Pentagon, the balloon was part of a massive surveillance operation that China has been operating for some years. According to the United States, Chinese balloons have flown over dozens of nations on five continents in recent years, and the US learnt more about the balloon operation after carefully watching the one shot down near South Carolina.

The 7th Fleet said in a press release that the combined operation had “established a robust presence in the area, which promotes peace and security.”

“As a rapid reaction force, we support a wide range of tasks, such as bringing Marines ashore, humanitarian disaster assistance, and deterring prospective enemies by visible and present combat might,” according to the announcement.