Taiwan’s defence ministry said 51 Chinese aircraft and six Chinese ships had been detected operating around Taiwan on Thursday, August 18 as China continues military activities near the island.

Out of the 51 aircrafts, 25 aircrafts crossed the Taiwan Strait’s median line, which in normal times acts as an unofficial barrier between the two sides, or flew into Taiwan’s air defence zone.

The move comes after the U.S. government said it will hold trade talks with Taiwan in a sign of support for the island democracy that China claims as its own territory, prompting Beijing to warn it will take action to ‘safeguard its sovereignty.’

Earlier in August, China fired missiles into the sea to intimidate Taiwan after U.S. House Speaker Nancy Pelosi became the highest-ranking American official to visit the island in 25 years.

After the US revealed it had started new trade talks with Taiwan – the self governed island that China has vowed to reunite by all means necessary, Chinese President Xi Jinping’s government criticized the planned talks as a violation of its stance that Taiwan has no right to foreign relations.

China warned the US not to encourage the island to try to make its de facto independence permanent, a step Beijing says would lead to war.

‘China firmly opposes this,’ Ministry of Commerce spokesperson Shu Jueting said. She called on Washington to ‘fully respect China’s core interests.’

Meanwhile, the US expects China to increase its military, diplomatic and economic ‘coercion’ of Taiwan, the US top envoy in East Asia Daniel Kritenbrink said on Thursday.

Daniel Kritenbrink’s warning comes a day after Taiwain’s military staged exercises to show its ability to resist Chinese pressure to accept Beijing’s political control over the self-governing island, following new rounds of threatening drills from China.

‘While our policy has not changed, what has changed is Beijing’s growing coercion,’ Kritenbrink, who is Washington’s top envoy for East Asian relations, told reporters on a teleconference call.

‘These actions are part of an intensified pressure campaign… to intimidate and coerce Taiwan and undermine its resilience,’ he added.

Also on Thursday, Taiwan’s military held a drill with missiles and cannons simulating a response to a Chinese missile attack.

Taiwan and China split in 1949 after a civil war and have no official relations but are bound by billions of dollars of trade and investment.

The United States has no diplomatic relations with Taiwan, its ninth-largest trading partner, but maintains extensive informal ties.