The US and China’s war of words have grown rapidly over the last few months over trade disputes and foreign policy. Washington recently denied Beijing’s control over the South China Sea, enraging China. The countries have also been trading sanctions over Huawei and Uighur muslim treatment by Beijing.
The E-8C, a US surveillance aircraft, was spotted near the southern province of Guangdong, China.
It is believed to be keeping check on Chinese military activity along the coastline.
The US operation was revealed on Twitter by the South China Sea Strategic Situation Probing Initiative, a Peking University think tank.
The E-8C was seen at Kadena airbase in Japan before flying to Guangdong, and was pictured above Tokyo early on Monday.
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The US planes have been sighted often near the Korean Peninsula to observe North Korean military movements.
E-8C’s flyover came as Taiwan began its largest annual military, the Han Kuang, exercise the same day.
The Han Kuang featured Taiwan’s new combined arms battalions.
Earlier this year Washington became closer allies with Taiwan, which infuriated China who sees Taiwan as a breakaway state.
China’s Southern Theatre Command claimed on WeChat that while the US was attempting to reassure Taiwan and other allies with its flyover, American forces may try to exploit the countries trust.
It is the latest US surveillance mission on Beijing, with last week seeing three planes monitor China’s coastline for three days straight.
The US also drew the anger of China when two USS aircraft carriers conducted defence drills in the South China Sea last month.
The drills were led by the USS Nimitz and Ronald Reagan “in support of a free and open Indo-Pacific”.
China threatened the US over the South China Sea drills, with the Southern Theatre Command warning of military action against the ships.
In a statement posted on WeChat, Southern Theatre Command said: “Chinese efforts to stabilise regional peace – while facing a US that is intent on making the South China Sea issue difficult – should be respected.
“It is easy to shake a mountain, but there is no way to shake the PLA.”