CHICAGO (CBS) — A northwest Indiana man who threatened to burn down or blow up abortion clinics in Chicago and Hammond, and then tipping off the FBI about his own threats, has been sentenced to 18 months in federal prison.

Luke Wiersma, 35, of Dyer, Ind., pleaded guilty last year to posting threats through the clinics’ websites at least seven times between October and November of 2017.

According to court documents, Wiersma claimed to be a member of an anti-abortion extremist group called the “Army of God,” and threatened violence against the clinics.

“Die, die, die motherf****r. I will blow up the clinic with you and the staff in it. Y’all are pieces of f*****g s***. I ain’t afraid of the feds and will taunt them just to prove it. This ain’t nothing but a thing to me. F*****g die pieces of s***. This is Gods retribution towards you and your kind. God is punishing you through me,” one of the threats stated.

“I will do everything and anything to stop the unmitigated murders of fetuses. I will do everything to stop the atrocities committed by your clinic every minute of every day at your clinic. You are all pieces of s*** and I will kill to stop these atrocities. I will blow you up if I have to, burn the clinic down. I will do whatever is necessary I swear to God I will. After that you are in God’s hands and He will do His thing,” another threat stated.

According to the FBI, Wiersma used the same phone from which he sent the threats to report an anonymous tip to the feds, and even mirrored same of the language from his threats.

“Luke Wiersma is a danger to society. He plans on committing crimes against abortion clinics. He has threatened to ‘do whatever is necessary to stop the unmitigated murders of fetuses at baby killing mills.’ I don’t know what he meant but I think he is possibly planning a violent attack. He is somebody who should be looked into,” the tip stated.

After the FBI obtained a search warrant for his phone, Wiersma admitted to making the threats and told agents he “never intended to hurt anyone.”