American aircraft carrier USS Theodore Roosevelt in the South China Sea (Picture: US Department of Defense).
China has told the United States to 'stop flexing muscles in the South China Sea', during closed-door talks between defence officials.
Representing the two world superpowers, US Defense Secretary Mark Esper and Chinese Defense Minister Wei Fenghe met in Bangkok to discuss tense relations.
According to a spokesperson, Mr Fenghe called on the US not to "provoke and escalate tensions" in the waters - which are rich in oil and gas reserves.
China claims most of the busy waterway, with military outposts on several artificial islands.
The US believes China of trying to intimidate Asian neighbours such as Brunei, Malaysia and Vietnam - also with claims to some shares of the sea, through large-scale militarisation.
The United States Navy regularly carries out “freedom of navigation” operations close to Chinese-occupied islands.
During the meeting, which Mr Esper has called an effort towards continued relations "focused on maintaining the international rules-based system" followed for decades, Mr Fenghe said:
"We [call on] the U.S. side to stop intervening in the South China Sea and stop military provocation in the South China Sea."
One day prior to the meeting, Mr Esper accused Beijing of "increasingly resorting to coercion and intimidation to advance its strategic objectives" in the area.
During the meeting, the pair also discussed recent protests in Hong Kong and democratic Taiwan - which is claimed by China.
Mr Fenghe said China would "not tolerate any Taiwan independence incident".
China has previously threatened to attack Taiwan if it moves towards independence.
The previous day, as Mr Esper criticised China's intimidation strategies, China marked the start of Taiwan's presidential election campaigns by sailing a carrier group into Taiwan Strait.