What is the Insurrection Act which Trump keeps threatening to use?

Donald Trump has threatened to invoke the Insurrection Act, giving him sweeping presidential powers over the deployment of the military in the US.

"Well, it's been invoked before," he said, when speaking to reporters this week. He repeatedly suggested he might invoke it during his first term - but never did.

What is the Insurrection Act? It gives the president the power to deploy the military or federalise National Guard troops inside the US to tackle domestic uprisings. It can be invoked when there are "unlawful obstructions, combinations or assemblages or rebellion" against the authority of the US government, the statute states.

The law gives the president the power to use the armed forces to enforce the laws of the United States in any state and to take action "to enforce those laws or to suppress the rebellion". President Thomas Jefferson signed it into law in 1807.

There is a long American tradition of keeping the military out of domestic affairs and such a move would normally need approval by Congress. What has Trump said about the act? The president told reporters on Monday so far it has not been necessary to invoke the Insurrection Act - but he would consider doing so.

"We have an Insurrection Act for a reason," Mr Trump said. "If people were being killed and courts were holding us up, or governors or mayors were holding us up, sure, I'd do that." On Tuesday, hundreds of Texas National Guard soldiers gathered at a training centre outside Chicago, Illinois.

A federal judge has temporarily barred troops from heading to Portland, Oregon - but another has allowed a deployment to proceed in Chicago, where federal agents have embarked on a sweeping crackdown on illegal immigration. Mr Trump sent the National Guard to Los Angeles over the summer and to Washington DC, as part of his law enforcement takeover there.

How does Trump define insurrection? Mr Trump became the first president to be impeached twice when in 2021 he was accused of inciting an insurrection following the deadly riots at the US Capitol. He has indicated he has a low bar for what he considers an insurrection.

The president mentioned the word several times on Monday, including when referencing Portland. "Portland is on fire.

Portland's been on fire for years. And not so much saving it - we have to save something else, because I think that's all insurrection, really criminal insurrection," he said in the Oval Office.

He later told Newsmax the situation in Portland was "pure insurrection". Has the act been used before? Yes, it has been invoked on dozens of occasions throughout American history.

But since the civil rights movement of the 1960s, its use has become "exceedingly rare.