Sulaiman Abu Ghaith was convicted in March on charges he conspired to kill Americans in his role as a spokesman for al-Qaida.
Lawyers were making arguments today in federal court in Manhattan. Prosecutors want life. His lawyer says 15 years is adequate.
After arguments, Judge Lewis Kaplan was to announce the sentence.
The Kuwaiti imam became the voice of al-Qaida recruitment videotapes after the Sept. 11, 2001, attacks.
He warned in one that "the storm of planes" wouldn't stop.