CHICAGO (CBS) — A 24-year-old Polish native who was arrested before the NATO Summit for allegedly bragging he could blow up a downtown bridge has pleaded guilty and was sentenced to four years in prison.

Sebastian “Sabi” Senakiewicz pleaded guilty to one felony count of falsely making a terrorist threat on Tuesday. Cook County Judge Nicholas Ford sentenced him to four years in prison, and recommended he serve his sentence in a boot camp, according to the Cook County State’s Attorney’s office. Senakiewicz also will be deported after completing his sentence.

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Senakiewicz, of the 3600 block of North Odell Avenue, was arrested on May 17, for allegedly bragging that was hiding explosives in a hollowed-out Harry Potter book. He also allegedly claimed he had a vehicle packed with explosives and weapons, and that he had enough homemade explosives to blow up a train overpass during the NATO Summit in May. He was also accused of making a Molotov cocktail before the summit.

He later admitted he had no explosives, and none were found at the home where he was staying in Chicago.

Prosecutors said Senakiewicz described himself as an anarchist and member of the notorious “Black Bloc” group, but was upset with the lack of chaos in Chicago leading up to the summit.

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Occupy Chicago activists said Senakieicz agreed to plead guilty to avoid facing an indefinite term in jail.

His attorney also blasted prosecutors for charging Senakiewicz over what supporters have said were simply drunken remarks to two undercover cops.

“Honestly, how serious was this case? Does this rise to the level of what this statute was designed for? No. Sabi is guilty of imprudent language,” attorney Jeff Frank said in a statement provided by Occupy Chicago. “That’s hardly grounds to extract a guilty plea for a serious felony, but that’s how Ms. Alvarez has chosen to spend the taxpayers resources.”

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Occupy Chicago has said the charges against Senakiewicz and terrorism charges against four others before the NATO Summit amounted to an effort by police and prosecutors to silence opposition to the NATO Summit, and to frighten peaceful protesters.