China fired ballistic missiles and deployed fighter jets and warships on Thursday as it began its largest-ever military exercises around Taiwan, a show of force sparked by U.S. House Speaker Nancy Pelosis visit to the island.

Pelosi was the highest-profile U.S. official to visit Taiwan in years. In retaliation, China launched a series of exercises in multiple zones around Taiwan, straddling some of the busiest shipping lanes in the world and at some points just 12 miles from the island’s shore.

The drills involved a “conventional missile firepower assault” in waters to the east of Taiwan, the Chinese military said.

The aim was to test the precision of the missiles and their ability to deny an enemy access to or control of an area, Eastern Theater Command spokesman Senior Colonel Shi Yi said in a statement.

Taiwan said the Chinese military fired several Dongfeng-class ballistic missiles, and condemned the exercises as “irrational actions that undermine regional peace”. Taipei didn’t say where the missiles landed or whether they flew over the island.