Acting US homeland security secretary Chad Wolf resigns

Wolf, who played key role in president's hardline immigration policies, says exit prompted in part by recent events'

Chad Wolf, the acting homeland security secretary, who helped enact key pieces of the Trump administration's hardline immigration agenda, resigned on Monday, as the nation confronts heightened security threats after an attack on the US capitol by supporters of the president.

Wolf said in a letter to staff at the Department of Homeland Security that he had intended to remain in office until the inauguration of Joe Biden but would instead step down at 11.59pm on Monday night.