President Donald Trump revealed on Monday that he is open to invoking the Insurrection Act to federalize the National Guard units in certain states, but noted it hasn’t been “necessary” so far.

“So far, it hasn’t been necessary, but we have an Insurrection Act for a reason. If I had to enact it, I’d do that,” Trump told reporters in the Oval Office when asked under what circumstances he would invoke the 19th-century federal law.