The Jewish High Holidays this year fall in early October, and that's when a massacre was planned against two Los Angeles synagogues, as well as other targets, according to an indictment just handed down against four young Muslim men.

Law enforcement traces the origins of this plot to 1997. That's when Kevin Lamar James, a black inmate at New Folsom Prison, near Sacramento, Calif., founded Jam'iyyat Ul-Islam Is-Saheeh (Arabic for"Assembly of Authentic Islam" and known as JIS). JIS promotes the sort of jihadi version of Islam typically found in American prisons As the indictment puts it, James, now 29, preached that JIS members have the duty"to target for violent attack any enemies of Islam or ‘infidels,' including the United States government and Jewish and non-Jewish supporters of Israel."

James, serving a 10-year prison sentence for an armed robbery in 1996, recruited acolytes among fellow inmates Volunteers swore to obey him and not to disclose the existence of JIS. On release from prison, they promised to get directives from him at least every three months, recruit Muslims to JIS, and attack government officials and supporters of Israel.

Levar Haney Washington, 25, allegedly joined the JIS and swore allegiance to James just before being released from New Folsom in November 2004, having served his six-year sentence for a 1999 assault and robbery. On getting out, Washington immediately began recruiting at his mosque, Jamat-E-Masijidul Islam in the Los Angeles area."He regarded Osama bin Laden very highly," reported one person whom Washington tried to recruit.

Two men, both 21 years old and without criminal records, did sign up: a lawful Pakistani immigrant and student at Santa Monica College, Hammad Riaz Samana; and a black convert who had worked at a duty-free shop in Los Angeles International Airport, Gregory Vernon Patterson The three, plus James, now face up to life in prison for conspiring"to levy a war against the Government of the United States through terrorism."

They did so in five ways. They conducted surveillance of American government targets (military recruitment stations and bases), Israeli targets (consulate in L.A. and El-Al airlines), and Jewish targets (synagogues). The trio monitored the Jewish calendar and, the indictment notes, planned to attack synagogues on Jewish holidays"to maximize the number of casualties."

They acquired an arsenal of weapons. To fund this undertaking, they set off on a crime wave, robbing (or attempting to rob) gas stations 11 times in the five weeks after May 30. They engaged in physical and firearms training. Finally, they tried recruiting other Muslims.

But Patterson dropped a mobile telephone during the course of one gas station robbery, and the police retrieved it. Information from the phone set off an FBI-led investigation that involved more than 25 agencies and 500 investigators. The police staked out Patterson and Washington, arresting them after they robbed a Chevron station on July 5. Washington's apartment turned up bulletproof vests, knives, jihad literature, and the addresses of potential targets. Patterson was waiting to acquire an AR-15 assault rifle.

The JIS story prompts some worried observations.

Although Attorney General Alberto R. Gonzales lavished praise on"the work of able investigators at all levels of government" in solving this case, law enforcement was as clueless about the JIS gang as was its British counterpart about the July 7 bombers. If not for the lucky break of a dropped phone, the jihadists probably would have struck. It is extremely disturbing to see law enforcement pat itself on the back for ineptitude.

American prisons are comparable to the banlieues in France, the principal recruiting grounds for a criminal form of Islam. As Frank Gaffney observes,"The alleged New Folsom State plot had better rouse us out of our stupor." Will it? Senate hearings in 2003 on prison jihadism yielded distressingly few results.

The emergence of a primarily African-American Islamist terrorist cell signals a new trend. Native-born Americans have taken part in terrorist operations before, but (again, as in London), this case this marks their first large-scale plot.

Terrorist plans that fail don't make headlines, but they should. This was a near-miss. Home-grown radical Islam has arrived and will do damage.

Even though most Jews resist acknowledging it, the Muslim threat is changing Jewish life in the United States. The golden age of American Jewry is coming to an end.

This article is reprinted with permission by Daniel Pipes. This article first appeared in the New York Sun.