A Brooklyn man who prosecutors say twice pledged allegiance to the Islamic State group and encouraged deadly “lone-wolf” attacks in New York City’s subways and elsewhere was sentenced Wednesday to 20 years in prison.

Zachary Clark’s penalty was announced in Manhattan federal court by Judge Naomi Reice Buchwald.

The judge said she wanted to send the message that “provide or attempt to provide materials or support to a foreign terrorist organization and you will spend a very long time in jail.”

The bearded Clark, in an orange prison jumpsuit and black glasses, tried along with his lawyer to persuade Buchwald that he had reformed himself behind bars since his November 2019 arrest, in part by attending drug and anger-management programs.

But the judge remained unconvinced. “I have no confidence Mr. Clark can be a productive and law abiding citizen,” Buchwald said as she ordered supervision for life once he is freed.

Clark, 42, pleaded guilty in August to attempting to provide support to the Islamic State group. The 20-year sentence was the maximum.

Prosecutors had requested it, noting that he posted maps and images of the subway system online in encrypted chat rooms, encouraged Islamic State supporters to attack it and urged “lone-wolf” attacks in the United States and elsewhere.