China carried out assault drills near Taiwan on Tuesday, with warships and fighter jets exercising off the southwest and southeast of the island in what the country's armed forces said was a response to "external interference" and "provocations".
Taiwan, which Beijing claims as Chinese territory, has complained of repeated People's Liberation Army (PLA) drills in its vicinity in the past two years or so, part of a pressure campaign to force the island to accept China's sovereignty.
In a brief statement, the PLA's Eastern Theatre Command said warships, anti-submarine aircraft and fighter jets had been dispatched close to Taiwan to carry out "joint fire assault and other drills using actual troops".
It did not give details.
A senior official familiar with Taiwan's security planning told Reuters that China's air force had carried out a "capturing air supremacy" drill, using their advanced J-16 fighters.
"In addition to seeking air supremacy over Taiwan, they have also been conducting frequent electronic reconnaissance and electronic interference operations," the person said.
Taiwan believes China is trying to gather electronic signals from U.S. and Japanese aircraft so that they can "paralyse reinforcing aircraft including F-35s in a war", the source said, referring to the U.S.-operated stealth fighter.
Taiwan's Defence Ministry said 11 Chinese aircraft entered its air defence zone, including two nuclear-capable H-6K bombers and six J-16 fighters, and that it had scrambled jets to warn China's planes away.
While the Chinese statement gave no exact location for the drills, Taiwan's Defence Ministry said the aircraft flew in an area between mainland Taiwan and the Taiwan-controlled Pratas Islands at the top part of the South China Sea.
Some of the aircraft also briefly entered the strategic Bashi Channel off southern Taiwan that leads to the Pacific, according to a map provided by the ministry.
"The nation's military has a full grasp and has made a full assessment of the situation in the Taiwan Strait region, as well as related developments at sea and in the air, and is prepared for various responses," it added.
The PLA statement noted that recently, the United States and Taiwan have "repeatedly colluded in provocation and sent serious wrong signals, severely infringing upon China's sovereignty, and severely undermining peace and stability in the Taiwan Strait".
"This exercise is a necessary action based on the current security situation across the Taiwan Strait and the need to safeguard national sovereignty. It is a solemn response to external interference and provocations by Taiwan independence forces."
It was not immediately clear what set off the flurry of Chinese military activity, though earlier this month, the United States approved a new arms sale package to Taiwan, an artillery system valued at up to $750 million.
China believes Taiwan President Tsai Ing-wen is a separatist bent on a formal declaration of independence, a red line for Beijing. Tsai said Taiwan is already an independent country called the Republic of China, its formal name.
Washington has expressed its concern about China's pattern of intimidation in the region, including towards Taiwan, reiterating that U.S. commitment to Taiwan is "rock solid".
China has never renounced the use of force to bring Taiwan under its control.