Former President Donald Trump is testing the tolerance of the judiciary, and perhaps even his own legal team, with belligerent messages about prosecutors, witnesses and judges involved in the criminal cases against him.

Trump already has disparaged former Vice President Mike Pence, who could be a key witness against him in a federal election interference trial, and urged former Georgia Lt. Gov. Geoff Duncan not to testify before a grand jury in Fulton County, Ga.

“If you go after me, I’m coming after you,” Trump posted on social media, a day after his arraignment in Washington, D.C., earlier this month.