An American supporter of al-Qaida who sought terrorist training abroad and hoped to carry out a plot to kill U.S. soldiers in Iraq has been sentenced to 17 and one-half years in prison.

The 29-year-old prisoner, Tarek Mehanna, was found guilty in December of seven criminal charges related to terrorism and lying about his activities. A crowd of supporters applauded Mehanna when his sentence was pronounced Thursday in a federal court in Boston.

Mehanna, a trained pharmacist, has been in custody since 2009, and the alleged murder plan never was carried out. He denied that he wanted to kill Americans, but testified that he felt “Muslims should defend themselves against foreign invaders.”

Defense lawyers said Mehanna was exercising his free-speech rights when he translated and posted on the Internet an al-Qaida manual on jihad and other documents calling on Muslims to rise up against non-believers and their oppressors. They asked for a sharply reduced sentence, but prosecutors recommended a 25-year prison term.

Government attorneys said Mehanna's goal was to murder American soldiers, and that he did not do so only because he was unable to find the terrorist training he was seeking when he traveled to Yemen in 2004. The defense said he was an aspiring scholar of Islam who went to Yemen for religious reasons.

Mehanna grew up in Massachusetts, in a wealthy suburb of Boston. Charges against him included conspiring to kill in a foreign country, providing material support to terrorists and lying to investigators in a terrorism case. In addition to his time in prison, the judge ordered that he should be supervised by federal authorities for seven and one-half years after he is released.