SEATTLE — When a judge who helped derail President Trump’s travel ban was hit with online threats, the abuse raised safety concerns among jurists across the country, and experts are worried that the president’s own attacks on the judiciary could make judges a more inviting target.

U.S. District Judge James Robart imposed the temporary restraining order that halted enforcement of Trump’s ban last week. The president soon sent a tweet saying the opinion of “this so-called judge” was “ridiculous and will be overturned.”

Robart quickly became a target on social media. Someone on Twitter called him a “DEAD MAN WALKING” and another on Facebook suggested that he be imprisoned at the military detention center at Guantanamo Bay, “where other enemies of the US are held.”

“I know there’s a fear among the judiciary with what’s being said,” said John Muffler, a former U.S. marshal who teaches security at the Reno, Nevada-based National Judicial College.

He cited professional contacts and email exchanges with judges.

The president’s critical comments have consequences, he added, because “people on the edge can easily be pushed over the edge once the rhetoric gets going.”

Trump blasted the federal court system again Wednesday after the 9th U.S. Circuit Court of Appeals heard arguments on whether Robart’s temporary restraining order should stand. During a speech to law enforcement officials, the president said the “courts seem to be so political” and called the hearing “disgraceful.”

The next day, White House spokesman Sean Spicer said Trump had “no regrets” about his criticism of judges.

Threats against judges are nothing new.

They often come in the form of emails, phone calls, letters and social media posts, according to court records and the U.S. Marshals Service, which is responsible for protecting the federal judiciary.

Trump’s Supreme Court nominee, Neil Gorsuch, has described the president’s criticism of the judiciary as “demoralizing and disheartening.”