The Arleigh Burke-class guided missile destroyer USS Barry conducted a "routine Taiwan Strait transit" on Friday, a statement from the US Navy's Seventh Fleet said.

"The ship's transit through the Taiwan Strait demonstrates the US commitment to a free and open Indo-Pacific", it said, adding that the US military "flies, sails, and operates anywhere international law allows".

In response, the People's Liberation Army's Eastern Theatre Command said it had closely monitored the passage of the USS Barry.

"The US has repeatedly taken provocative actions, which illustrates that the US is the biggest troublemaker for the stability of the Taiwan Strait," a spokesman for the theatre command said.

"The theatre command remains on high alert and is determined to safeguard national sovereignty, security and regional peace and stability."

The theatre command on -Friday deployed naval and air -forces, including combat ships, early warning aircraft and -bombers, to carry out joint patrols and combat drills in the waters and seas to the southwest of -Taiwan, the spokesman said in a separate statement.

"The relevant actions (were) aimed at improving the integrated and joint combat capabilities of theatre forces, and will be organised in a regular manner in accordance with the situation in the Taiwan Strait and the need to maintain national sovereignty and security," the statement said.

Taiwan's defence ministry said the mainland military deployment included six J-16 and two J-11 fighters, as well as one anti-submarine and one reconnaissance aircraft.

Taiwan sent combat aircraft to warn away the Chinese aircraft, while missile systems were deployed to monitor them, the ministry said.

The Chinese fighter jets flew in an area close to the disputed Pratas islands, governed by Taipei but claimed by Beijing, while the anti-submarine and reconnaissance aircraft flew into the Bashi Channel, which separates Taiwan from the Philippines, according to a map issued by the ministry.

On Thursday, Taiwan announced it was planning to spend NT$240 billion (US$8.7 billion) over the next five years on domestically produced arms, including missiles capable of striking mainland China.

A special budget to buy several types of missiles - including Wan Chien (Ten Thousand Swords) cruise missiles, Tien Kung (Sky Bow) anti-ballistic missiles, short-range Tien Chien (Sky Sword) and medium-range Hsiung Feng (Brave Wind) missiles - was approved by the cabinet on Thursday.

Beijing considers Taiwan to be part of its territory and has not ruled out the use of force to bring it back under its control.

Taiwanese Premier Su Tseng-chang said the government had to take the threat from the mainland seriously.

"The Chinese Communists plot against us constantly," he said.

Additional reporting by Lawrence Chung

Copyright (c) 2021. South China Morning Post Publishers Ltd. All rights reserved.

• China enters Taiwan air defense zone a day after military budget boost
• China raps US-Britain-Australia security partnership

RELATED VIDEO FROM THE ARCHIVES

Watch more in iWantv or TFC.tv