At Sunday night's Tony Awards, the 74-year old actor, introducing Bruce Springsteen, stood before the cameras and told the world, literally, "Fuck Trump."
The CBS network was able to bleep out the statement before it hit homes in the U.S., but it didn't take long for viewers in less puritanical nations to post the video – uncensored – to social media.
Late Tuesday afternoon the president took two full tweets to attack the "Raging Bull" and "Cape Fear" star.
But Trump, perhaps still jet-lagged, was clearly off his game.
Recycling his infamous slam, "low IQ," the president blasted "punch-drunk" De Niro:
...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. Wake up Punchy!
— Donald J. Trump (@realDonaldTrump) June 12, 2018
The president has used the same "low IQ" slur against Washington Post conservative blogger Jennifer Rubin, U.S. Congresswoman Maxine Waters, and "Morning Joe" co-host Mika Brzezinski.