A US warship sailed through the sensitive Taiwan Strait on Saturday, as part of what the American military calls routine activity that nonetheless irritates China. The US Navy’s 7th Fleet said its Arleigh Burke-class guided-missile destroyer USS Ralph Johnson was conducting a “routine” transit through international waters. “The ship’s transit through the Taiwan Strait demonstrates the United States’ commitment to a free and open Indo-Pacific,” 7th Fleet spokesperson Nicholas Lingo said in a statement. “The United States military flies, sails, and operates anywhere international law allows.” Beijing’s defence ministry did not immediately respond to a request for comment. The Taiwanese defence ministry said its navy monitored the whole process when the ship passed through the strait and described the passage as “normal”. US warship transits South China Sea to challenge ‘unlawful maritime claims’ Last year, US naval ships made roughly monthly transits through the strait. Saturday’s sailing was the first since November. Beijing claims democratically ruled Taiwan as its own territory and has mounted repeated air force missions into the island’s air defence identification zone over the past two years, provoking anger in Taipei. Beijing also calls Taiwan the most sensitive and important issue in its relations with Washington. Like most countries, the United States has no formal diplomatic ties with Taiwan but is its most important international backer and arms supplier. Additional reporting by Josephine Ma