U.S. President Donald Trump on Monday signed an executive order designating Antifa as "a domestic terrorist organization," 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 organization," the White House said in a document.

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

The order directs the federal government to "investigate, disrupt, and dismantle all illegal operations" conducted by Antifa or any person claiming to act on behalf of Antifa. It also calls for "necessary investigatory and prosecutorial actions against those who fund such operations."

"Antifa's terror is part of the trend of Radical Left violence that has permeated the nation in recent years, incited by constant lies and vicious attacks against Republicans from unhinged Democrat politicians, well-funded leftist organizations, and their allies in the media," said the document, adding that conservative activist Charlie Kirk was killed by a "Radical Left terrorist."

"There is no legal authority to actually designate a domestic group as a terrorist organization even assuming that antifa is an organization and not just an ideology," Mary McCord, a former acting head of the Justice Department's national security division, was quoted by The New York Times as saying.

A report by The Washington Post also noted that the United States has no legal means of designating domestic terrorist groups, adding that experts expressed concern that the move could be used to justify a crackdown on the political left more generally.

During his first term in 2020, Trump also announced that he would designate the "Antifa" movement as "a terrorist organization," largely a response to the nationwide protests and unrest that erupted after the killing of African American George Floyd by police. But no concrete action was taken.

Trump signed the latest executive order amid a heated domestic debate over political violence following the death of Charlie Kirk. In response to Democrats' argument that both the left and right engage in political violence, Trump recently claimed that "most of the violence is on the left."