Trump counterpunches Robert De Niro, calling the actor 'a very Low IQ individual'

"I watched him ... and truly believe he may be 'punch-drunk,'" Trump tweets.

While introducing Bruce Springsteen at the awards ceremony Sunday night, De Niro was bleeped when he said: "First, I wanna say, 'F--k Trump. It's no longer 'Down with Trump,' it's 'F--k Trump.'"

This was not the first time the Oscar-winning actor attacked Trump so publicly -- and so colorfully.

In January, he also railed against Trump while introducing Meryl Streep at the National Board of Review Annual Awards Gala.

"Our baby-in-chief -- the j---off-in-chief, I call him -- has put the press under siege, ridiculing it and trying to discredit it through outrageous attacks and lies," De Niro said, comparing the Trump administration's attacks on the media to former President Richard Nixon's.

And in 2016, De Niro, who endorsed Democratic presidential nominee Hillary Clinton at the time, attacked Trump in a video, urging people to vote and saying, "I'd like to punch him in the face."