Chinese President Xi Jinping has instructed the country's army to increase military pressure in the southwestern region of Taiwan, sources familiar with the matter said Tuesday.

Xi's instruction came at a recent meeting of the Central Military Commission, China's highest military authority, after six democratic nations including the United States and Japan carried out joint military drills near Taiwan earlier this month involving three aircraft carriers.

A large number of Chinese military planes have entered Taiwan's air defense identification zone since last Friday, in an apparent bid to counter the military exercises conducted by Britain, Canada, Japan, the Netherlands, New Zealand and the United States.

Three U.S. and British aircraft carriers take part in a joint drill with Japanese Maritime Self-Defense Force ships in waters southwest of Okinawa in early October, 2021. (Photo courtesy of MSDF)(Kyodo)

Xi is believed to think that the military drills in waters southwest of Okinawa, Japan's southernmost prefecture, were designed to prevent China from unifying democratic Taiwan with the mainland and from gaining the Tokyo-controlled Senkaku Islands, claimed by Beijing.

On Monday, the United States criticized the Communist-led government over the intrusion of 56 Chinese military planes into Taiwan's air defense identification zone, saying it undermined regional peace and stability.

White House Press Secretary Jen Psaki said the United States urges China to cease its military, diplomatic, and economic pressure and coercion against Taiwan.

"Our commitment to Taiwan is rock solid and contributes to the maintenance of peace and stability across the Taiwan Strait and within the region," Psaki said.

The incursion by the military planes, a one-day record since the self-governed island began disclosing such figures in September last year, brought to 149 the number of the planes that have intruded so far this month.

The world has seen that China is violating regional peace and pressuring Taiwan, Premier Su Tseng-chang said Tuesday, calling its people to come together as one and strengthen the island.

At the Central Military Commission, Xi, commander-in-chief of the armed forces, said China should show that it is "always ready to fight," but in reality, the mainland wants to avoid a head-on confrontation with the United States, the sources said.

In March 1996, then U.S. President Bill Clinton ordered two aircraft carrier battle groups into waters off Taiwan's southern coast to tackle China's threats against the island before its first presidential election.

China and Taiwan have been separately governed since they split in 1949 as a result of a civil war. Their relations have deteriorated since independence-leaning Tsai Ing-wen became Taiwan's president in 2016. The mainland considers the island as a renegade province.