China on Thursday fired 11 ballistic missiles in the sea surrounding Taiwan during its largest-ever military drills following a visit by senior United States politician Nancy Pelosi to the island, the BBC reported.

China has been conducting military drills and sending fighter jets since Pelosi visited the country. On Wednesday, 27 Chinese fighter jets flew into Taiwan’s air defence zone, the island country’s defence ministry said on Thursday.

Taiwan said that it dispatched aircraft, issued radio warnings and deployed air defence systems to “monitor the activities” of the Chinese fighter jets.

Pelosi was the highest-ranking American official to visit Taiwan in 25 years despite a slew of threats from Beijing. China sees official visits by US authorities as lending support to pro-independence camps and giving credence to the idea of Taiwan as a sovereign nation.

China considers Taiwan as an island that is to be unified with the mainland.

On Thursday, Japan said that five Chinese missiles landed in its waters as well. It called for an “immediate stop” to the exercises, the BBC reported.

A day after the missile launch, Taiwan described China as its “evil neighbour”, Reuters reported. Taiwan Premier Su Tseng-chang told reporters that China is arbitrarily destroying the world’s most frequently-used waterway through its military exercises.

Pelosi, who is in Tokyo, said that the US will not allow China to isolate Taiwan, AFP reported.

“We had high-level visits, senators in the spring, the bi-partisan way, continuing visits, and we will not allow them to isolate Taiwan,” she said.

Pelosi said that her visits to Asian countries, including Taiwan, were not about changing the status quo in the region. It is more about the Taiwan Relations Act and the US-China policy, she added.

The Taiwan Relations Act obliges Washington to ensure that the island has sufficient defence capability.