WASHINGTON

US President Donald Trump signed an executive order on Monday that seeks to punish anyone who burns an American flag with one year in prison, despite a long-standing Supreme Court precedent protecting the controversial practice.

Trump appeared set to line up a new challenge to the ruling on allegations that burning the flag could result in public disorder and incite people to riot.

"What happens when you burn a flag is the area goes crazy. If you have hundreds of people, they go crazy. You can do other things. You can burn this piece of paper, but when you burn the American flag, it incites riots at levels that we've never seen before," he said.

"People go crazy, in a way, both ways. There are some that are going crazy for doing it. There are others that are angry, angry about them doing it," he added.

The Supreme Court ruled in 1989 that burning the American flag is lawful under the First Amendment's free speech protections. But Trump's order directs Attorney General Pam Bondi to "vigorously prosecute those who violate our laws in ways that involve desecrating the American Flag, and may pursue litigation to clarify the scope of the First Amendment exceptions in this area."

Flag burning was seen at mass demonstrations in Los Angeles protesting Trump's decision to deploy the National Guard to America's second-largest city to bolster his ongoing immigration crackdown there.