"Robert De Niro, a very Low IQ individual, has received to many shots to the head by real boxers in movies. I watched him last night and truly believe he may be 'punch-drunk,'" Trump tweeted while on his way home from Singapore, where he attended a first-of-its-kind summit with North Korean leader Kim Jong Un.
"I guess he doesn't realize the economy is the best it's ever been with employment being at an all time high, and many companies pouring back into our country," Trump added. "Wake up Punchy!"
De Niro had some thoughts to get off his chest before introducing Bruce Springsteen on Sunday.
"I'm going to say one thing," he said, raising his fists in the air. "Fuck Trump. It's no longer down with Trump. It's fuck Trump. In these perilous times, you rock the vote, always fighting for truth, transparency and integrity in government. Boy, do we need that now!"
The audience went wild, offering a standing ovation.
De Niro continued to rant against Trump the next day, apologizing to Canada for "the idiotic behavior of my president."
"It's a disgrace, and I apologize to [Canadian Prime Minister] Justin Trudeau, too, and the other people at the G-7," De Niro said Monday while in Toronto.
De Niro has gone on tirades against Trump before. During a speech at the National Board of Review's annual awards gala in January, he referred to the president as a "fucking idiot," a "fucking fool, a "baby-in-chief" and a "jerkoff-in-chief."