Two Su-35 fighter jets and a H-6K bomber fly in formation on May 11, 2018. Photo:Xinhua

The Chinese People's Liberation Army (PLA) monitored the flyover of a US spy aircraft over the Taiwan Straits on Friday, vowing to safeguard national sovereignty and territorial integrity amid large-scale military drills in the region in response to repeated provocations by the "Taiwan independence" secessionists and US, Japanese interference forces.

US' move is particularly provocative as it is the first US military activity in the region after China made it clear that there are no "international waters" in the Taiwan Straits, observers said.

The US sent a P-8A anti-submarine aircraft which flew over the Taiwan Straits on Friday and publicly hyped this move. The PLA Eastern Theater Command organized aerial and ground forces and tracked and monitored its movement throughout its entire course on high alert, Senior Colonel Shi Yi, spokesperson of the PLA Eastern Theater Command, said in a statement on Saturday.

Shi slammed US' move as intentional to disrupt the regional situation and endanger the cross-Straits peace and stability. "We firmly oppose this," she said. 

The PLA Eastern Theater Command is on high vigilance all the time and will resolutely safeguard national sovereignty and territorial integrity, Shi said.

Chinese Foreign Ministry spokesperson Wang Wenbin made it clear earlier this month that there is no such thing as "international waters" on the United Nations Convention on the Law of the Sea, and that China has sovereignty, sovereign rights and jurisdiction over the Taiwan Straits.

The US provocatively sends warships through the Taiwan Straits on a monthly basis, but it has not sent one in June as of yet, and instead has sent a military aircraft. This could be a US "salami-slicing" tactic to test China's determination, and while no warships were sent, the move is very provocative right after China's remarks on the status of the Taiwan Straits, a Beijing-based military expert told the Global Times on Saturday, requesting anonymity.

By organizing aerial and ground forces to track and monitor the US spy aircraft activity, the PLA likely sortied warplanes and deployed radars of surface-to-air missile systems, the expert said.

The PLA must still remain high alert for a US warship transit in the Taiwan Straits, the expert said.

In an apparent response to recent repeated provocations by the "Taiwan independence" secessionists and US, Japanese interference forces, the PLA reportedly held large-scale military drills around the island of Taiwan this week, sending dozens of warplanes, including fighter jets, bombers and early warning aircraft, and a number of warships, including destroyers and frigates, to the southwest and east of the island of Taiwan, and east and south to Japan.