Taiwan said Saturday that China’s military drills appear to simulate an attack on the self-ruled island, after multiple Chinese warships and aircraft crossed the median line of the Taiwan Strait following US House Speaker Nancy Pelosi’s visit to Taipei that infuriated Beijing.

Taiwan’s armed forces issued an alert, dispatched air and naval patrols around the island, and activated land-based missile systems in response to the Chinese exercises, Taiwan’s Ministry of National Defense said on Twitter. China launched live-fire military drills following Pelosi’s trip to Taiwan earlier this week, saying that it violated the one-China policy. China sees the island as a breakaway province to be annexed by force if necessary, and considers visits to Taiwan by foreign officials as recognising its sovereignty. Taiwan’s army also said it detected four unmanned aerial vehicles flying in the vicinity of the offshore county of Kinmen, Taiwan’s news agency reported.