Why has China lodged a complaint with Canada over a warship?

China has lodged complaints withCanada through military and diplomatic channels after a Canadian warship sailed through the Taiwan Strait, the Chinese defence ministry said on Friday.

The act “caused disturbance and stirred up trouble,” the ministry said in a statement.

“We warn Canada that it should abide by the One-China Principle, be cautious in its words and deeds on the Taiwan issue,” ministry spokesperson Zhang Xiaogang said.

The frigate passed through the Taiwan Strait in what Ottawa called a commitment to an open Indo-Pacific, drawing a rebuke from China that the naval exercise on July 31 undermined peace.

Canada’s Department of National Defence said HMCS Montreal had “recently conducted a routine transit” through the strait in what Defence Minister Bill Blair said was a reaffirmation of Canada’s commitment to a “free, open and inclusive” Indo-Pacific.

“As outlined in our Indo-Pacific Strategy, Canada is increasing the presence of the Royal Canadian Navy in the Indo-Pacific region,” Blair said, referring to Canada’s plan for the region announced in 2022.

Li Xi, a spokesperson for the People’s Liberation Army’s (PLA) Eastern Theater Command, said the passage of the Canadian frigate had “harassed and disrupted the situation and undermined peace and stability across the Taiwan Strait.”

China’s troops, he added, were on high alert at all times and are “ready to respond to all threats and provocations.”

China claims sovereignty over democratically governed Taiwan, and says it has jurisdiction over the nearly 180kilometre-wide waterway dividing the two sides.