Washington, Sept. 23 -- U.S. President Donald Trump on Monday signed an executive order designating Antifa as "a domestic terrorist organisation," a move some experts believe lacks legal authority.

"President Donald J. Trump is right: the violence problem is on the Left. That's why he just designated Antifa -- a network of Radical Left terrorists that aim to overthrow the government through violence and agitation -- as a domestic terrorist organisation," the White House said in a document.

It also lists examples of the movement's "long history of terrorising our communities," including attacks on U.S. Immigration and Customs Enforcement officers, police officers, attendees of conservative political events, and Trump supporters.

The order...