An Indiana anti-abortion activist was sentenced Tuesday to a year and a half in federal prison for sending a series of online death threats to Chicago-area abortion clinics — acts the judge denounced as terrorism.

In rejecting a defense plea for home detention for Luke Wiersma, U.S. District Judge Manish Shah said a message needed to be sent that making online threats — however easy it may be — has “no place here.”

“Using threats of violence as a means to advance an agenda … is terrorism,” the judge told Wiersma. “Too many people think this is an available tool to intimidate a perceived enemy, but it’s not. It’s a serious federal offense.”

Read more: Chicago Tribune