German and American investigators said that the explosives packed inside Hewlett-Packard computer printers and addressed to Chicago synagogues were four to five times more powerful than al-Qaida explosives used in past terror plots, and they were intended to detonate in the skies over Chicago.
As authorities in the U.S. and overseas scan packages for more hidden explosives, Jewish organizations in Chicago are still on edge.
Security video, along with two written warnings, has been sent to 170 Jewish institutions across metro Chicago at the request of law enforcement.
The warnings are:
- A security alert from the Jewish Federation encouraging synagogues to be on the lookout for any mail postmarked Yemen, especially suspicious packages, and to evacuate and call 911 if one is found.
- And a bulletin from the Anti-Defamation League recommending Jewish institutions "increase mailroom security" for anything "from overseas."
"I think people have remained relatively calm," said Lonnie Nasatir of the Anti-Defamation League. "The majority of people that have contacted us were not hysterical but they wanted they know more they could do which is responsible."
The bombs headed to Chicago contained slightly less than one pound of the highly explosive chemical powder PETN, a nitro-glycerin-style compound.
By comparison, in the plot to blow up a passenger jet over Detroit last Christmas, about 1/16th of a pound of PETN was found.
In 2001, shoe-bomber Richard Reid was carrying even less than that during his failed attempt to blow up a U.S.-bound jetliner.
Investigators say the same bomb maker, Ibrahim Al-Asiri, is behind all three incidents. Saudi national Al-Asiri, 28, is thought to be so ruthless that he once planted explosives on his own brother to kill a target.
The package bombs might have made it to Chicago had Jabir Jubran Al Fayfi, an al-Qaida turncoat who surrendered to Saudi authorities last month, not given up information about the synagogue plot.
Al Fayfi was held as an enemy combatant in U.S. custody at Guantanamo Bay for six years after his capture in 2001 in Afghanistan.
He was released to Saudi Arabia for terrorist "rehab," but he quickly escaped to Yemen where he resumed work for Al Qaeda until last month.
Shortly after Al Fayfi began working with Saudi intelligence, authorities in the U.S. intercepted what they now believe was a dry run shipment to Chicago.
More than a month ago, a carton of religious books and computer disks was shipped from Yemen to Chicago by an known al-Qaida operative.
An intelligence source has told ABC News was a test of the system to gauge the timing of the cargo flight so that terrorists could blow up the jetliner directly over Chicago.