The P-8A Poseidon aircraft transited the strait in international airspace to demonstrate "the United States' commitment to a free and open Indo-Pacific", the US Seventh Fleet said.

Beijing claims self-ruled Taiwan as its territory, reacting angrily in the past to voyages by foreign warships or military aircraft through the narrow waterway separating the island and mainland China.

Taiwan's defence ministry said 26 Chinese warplanes were detected around the island on Thursday, with 13 crossing the island's southwestern air defence identification zone "to carry out joint sea and naval trainings with communist Chinese ships".

The ministry said the island's forces had also closely monitored the US aircraft's transit through the strait.

"The United States military flies, sails and operates anywhere international law allows," the US Navy said in its statement.

Beijing has ratcheted up military and political pressure on Taiwan in recent years, staging "long-range joint air and naval exercises" around the island on Wednesday, according to Taipei's defence ministry.

The exercises came as Santiago Pena, the visiting president-elect of Paraguay, Taipei's sole ally in South America, vowed to be on Taiwan's side at a meeting with Taiwanese leader Tsai Ing-wen.

In April, China's military said it sent fighter jets to track a P-8A as it flew through the Taiwan Strait, following another transit in February that prompted a similar response from Beijing.

The P-8A is used for a variety of missions, including reconnaissance and anti-submarine warfare, according to its maker Boeing.

Last month, US and Canadian warships sailed through the strait in a joint mission, which Beijing slammed as "intentionally creating trouble" in the area.

aw/aha

BOEING