Chinese fighter jets have crossed the Taiwan Strait, local media reported  as tensions flare over an visit to Taiwan by US House Speaker Nancy Pelosi. Pelosi is the highest-ranked American politican to visit the island in 25 years.

“China’s Su-35 fighter jets are crossing the Taiwan Straits,” state TV CGTN reported, without adding further details.

The Chinese leadership has repeatedly warned against Pelosi, a long-time critic of Beijing, making a trip to self-ruled Taiwan. China regards Taiwan as part of its territory and has vowed an unspecified military response to any Pelosi visit that risks sparking a crisis between the world’s biggest economies.

Earlier today, four US warships, including an aircraft carrier, were positioned in waters east of Taiwan on what the country’s Navy called routine deployments.