A U.S. Navy patrol plane flew through the Taiwan Strait on Friday as a senior French lawmaker confirmed a warship from his country had also recently transited the sensitive waterway, amid growing tension between Beijing and Taipei.

China, which views democratically governed Taiwan as its own territory, has increased military pressure on the island over the past three years as it tries to force Taipei to accept it sovereignty claim.

This month, China staged war games around Taiwan after Taiwan President Tsai Ing-wen met U.S. House of Representatives Speaker Kevin McCarthy in Los Angeles.

The United States, and occasionally its allies, have been routinely sending warships through the Taiwan Strait in recent years, and sometimes fly aircraft through it too.

The U.S. Navy’s 7th Fleet said a P-8A Poseidon maritime patrol and reconnaissance plane flew through the Taiwan Strait in international airspace.

“By operating within the Taiwan Strait in accordance with international law, the United States upholds the navigational rights and freedoms of all nations,” it said in a statement.

“The aircraft’s transit of the Taiwan Strait demonstrates the United States’ commitment to a free and open Indo-Pacific.”

China said last year that it has sovereignty, sovereign rights and jurisdiction over the Taiwan Strait, and referred to assertions that the Taiwan Strait was international waters was “a false claim”.

The United States and Taiwan have both refuted China’s position.

Meeting Tsai at her office in Taipei on Friday, a French lawmaker and former defence minister said his country had recently sailed a warship through the strait.

“I want to tell you that our parliament’s view is that the security of Taiwan is an important concern for us and we are encouraging our authorities to stay alert on security in the Strait, as the recent passage of our warship has again demonstrated,” French Senate Vice President Alain Richard said.

He did not say when the sailing happened, and neither the French nor Taiwanese governments has officially confirmed details. Taiwan’s defence ministry said this month it was aware of the transit.

French President Emmanuel Macron has recently warned against being drawn into a crisis over Taiwan driven by an “American rhythm and a Chinese overreaction”.