The attack has stoked fears about politically motivated violence a week before midterm elections that will decide control of Congress during one of the most vitriolic and polarised campaign seasons in decades.

David Wayne DePape has been charged with assault and attempted kidnapping, with separate state charges filed for attempted murder, assault with a deadly weapon, burglary, elder abuse and threatening a public official.

Making the highest-level visit to Taiwan by a US official in 25 years, Pelosi praised its democracy and pledged solidarity, enraging China.

Pelosi arrived in South Korea following a brief stop in Taiwan, and met US embassy officials in Seoul earlier before talks with speaker Kim Jin-pyo and other lawmakers.

China demonstrated its outrage over the highest-level US visit to the island in 25 years with a burst of military activity in surrounding waters, summoning the US ambassador in Beijing and halting several agricultural imports from Taiwan.