Disclosure of a plot by four ex-convicts — three Americans and a Haitian — to bomb synagogues and attack aircraft in New York City and upstate Newburgh, N.Y., highlights the intersection between social pathologies in the African-American community, radical Islam, and derivatives of the latter, especially in prisons.

The defendants in the case were arrested on Wednesday, May 20. They are James "Abdul Rahman" Cromitie, whose age, somewhere between 44 and 55, is unconfirmed; David "Daoud" Williams, 28; Onta "Hamza" Williams, 32; and 27-year-old Laguerre "Amin" Payen — the original given name of the latter, curiously, means "war." They have been charged with conspiracy to use weapons of mass destruction in the U.S. and to acquire and use Stinger anti-aircraft missiles.

Cromitie, the leader of the group and a resident of Newburgh, claimed to have lived in Afghanistan and to have made contact with the Pakistani jihadist organization Jaish-e-Muhammad (Muhammad's Army), which mainly aims its violence at embattled Kashmir, claimed by Pakistan and India. JEM was designated a terrorist organization by the U.S. government in 2003. But it and its associated organization, Lashkar-e-Taiba (Army of the Righteous), which has been blamed for the Mumbai atrocities late last year, enjoy support among radical Pakistanis in Britain and the U.S.

According to the Associated Press, the men became acquainted with each other and with jihadist ideology while incarcerated. Prison brought the quartet together and the subcultures of prison extremism remained a constant factor in their lives.

As habitual criminals, the four men seem more characteristic of a gang-style phenomenon known as "prison Islam," in which drug users and other offenders adopt Islamic trappings to intimidate other inmates, than of the Nation of Islam or the Wahhabism that has been introduced into many American prisons by extremist chaplains.

But under the tutelage of Cromitie, they appear to have graduated from "prison Islam" to serious jihadist ambitions. The Daily News reports that Cromitie, on his way to a Philadelphia meeting of the Muslim Alliance in North America (MANA), spewed threats to "destroy a synagogue." MANA is led, according to its website, by Siraj Wahhaj, one of the most flamboyant hate mongers in American Islam. The website also claims support for MANA from the supposed "Sufi" and "peace apostle" Hamza Yusuf Hanson and his associate Zaid Shakur, as well as other prominent Islamists, such as Ihsan Bagby and Abdul Hakim Jackson.

The pattern of prison conversion, followed by release and the pursuit of terrorist intentions, is not new. A similar scheme by a group calling itself Jam'iyyat Ul-Islam Is-Saheeh (Assembly of Authentic Islam) originated at New Folsom Prison in California and was preempted by police action in Los Angeles in 2005. In 2007, the chief actors in the Folsom group, Levar Haley Washington and Kevin James, pleaded guilty to sedition charges. Washington was sentenced last year to 22 years in prison and James, early in 2009, to 16 years. Washington's sentence was augmented by an additional 22 years for his involvement in a gas station robbery. Another participant, Gregory Patterson, was penalized with 151 months incarceration.

Prison Islamization and radicalization remain a major threat around the world, including in Western Europe and Russia, as well as the U.S. Unfortunately, correctional authorities have lagged behind police bodies and prosecutors in dealing with the danger. Moderate Muslims must assist authorities in non-Muslim countries in combating this very real menace, by helping remove radical chaplains and literature from prisons and otherwise taking the fight against extremism into the prison environment.

Imaad Malik is the prison outreach director for the Center for Islamic Pluralism in Washington, D.C.