His ire was aimed at US District Judge James Robart, who last week put a nationwide hold on Trump's executive order barring citizens of seven Muslim-majority countries from entering the US for 90 days, all refugees for 120 days and indefinitely halts refugees from Syria.
"Just cannot believe a judge would put our country in such peril. If something happens blame him and court system. People pouring in. Bad!" the President wrote, not just attacking the decision but going after the judge who may yet make more decisions on the matter.
This came after a Saturday tweetstorm where Trump called Robart a "so-called judge."
People close to the White House said over the weekend that Trump's attacks will be a problem -- particularly as his administration shepherds his Supreme Court nominee Neil Gorsuch toward confirmation.
"No one was happy the President attacked the judge," one official said.
And Senate Majority Leader Mitch McConnell told CNN's Jake Tapper on "State of the Union" its not the best idea to attack judges.
"I think it's best not to single out judges for criticism. We all get disappointed from time to time," he said Sunday, before Trump's latest tweet.
Despite that feeling, Trump did it again Sunday, tweeting that Robart deserves blame for putting the United States "in peril."
He then added: "I have instructed Homeland Security to check people coming into our country VERY CAREFULLY. The courts are making the job very difficult!"
The incident recalls Trump's attacks on the campaign trail on Judge Gonzalo Curiel, an Indiana-born judge with Mexican ancestry, who Trump accused of making rulings in the Trump University class action lawsuit because he is "Mexican."
"We are building a wall. He's a Mexican," Trump told CNN's Jake Tapper during the campaign. "We're building a wall between here and Mexico."