China said Thursday its troops were "on constant high alert" after United States and Canadian warships passed through the Taiwan Strait.

The USS Rafael Peralta, an Arleigh Burke-class destroyer, and the Royal Canadian Navy's Halifax-class frigate HMCS Ottawa conducted a "routine" transit through the strait on Wednesday, the US Navy said.

"Troops in the theater remain on constant high alert, and will resolutely protect national sovereignty and security as well as regional peace and stability," Senior Colonel Shi Yi, a spokesperson for China's Eastern Theater Command, said in a statement.

Shi slammed the latest transit as a "public hype" and said its naval and air forces had "trailed their entire course."

The ships' passage comes after two warships belonging to the US and Canada sailed through the narrow waterway separating the island and mainland China on 9 September.

The US and its Western allies have increased "freedom of navigation" crossings by naval vessels both of the Taiwan Strait and the disputed South China Sea, to reinforce that both are international waterways, angering Beijing.