When, not if.

British intelligence and law enforcement officials have passed on a grim assessment to their U.S. counterparts, “It will be a miracle if there isn’t a terror attack over the holidays in London,” a senior American law enforcement official tells ABCNews.com.

British police have been quietly carrying out a series of key arrests as they continue to track at least six active “plots” tied to what they call “al Qaeda of England.”

Officials said they could not cite any specific date or target but said al Qaeda had planned previous operations during the Christmas holidays that had been disrupted…

Authorities say they are seeking at least 18 suspected suicide bombers

British law enforcement and intelligence officials say the ongoing plots have been in the planning stages for at least three years.

U.S. officials who spoke to the Blotter say they’re getting intelligence reports that corroborate this story in Newsweek.

For the past year, a secret has been slowly spreading among Taliban commanders in Afghanistan: a 12-man team of Westerners was being trained by Al Qaeda in Pakistan for a special mission. Most of the Afghan fighters could rely only on hearsay, but some told of seeing the “English brothers” (as the foreign recruits were nicknamed for their shared language) in person. One eyewitness, a former Guantánamo detainee with close Taliban and Qaeda ties, spoke to NEWSWEEK recently in southern Afghanistan, demanding anonymity because he doesn’t want the Americans looking for him. He says he met the 12 recruits in November 2005, at a mud-brick compound near the North Waziristan town of Mir Ali. That was as much as the tight-lipped former detainee would divulge, except to mention that Adam Yahiye Gadahn, the notorious fugitive “American Al Qaeda,” was with the brothers, presumably as an interpreter.

Another Afghan had more to say on the subject. Omar Farooqi is the nom de guerre of a former provincial intelligence chief for the Taliban; he now serves as the Taliban’s chief Qaeda liaison for Ghazni province, in eastern Afghanistan. He says he spent roughly five weeks this past year helping to indoctrinate and train a class of foreign recruits near the Afghan border in tribal Waziristan, and among his students were the English brothers. The 12 included two Norwegian Muslims and an Australian, along with nine British subjects, says Farooqi. Their mission, Farooqi told NEWSWEEK, will be to act as underground organizers and operatives for Al Qaeda in their home countries—and their yearlong training course is just about finished…

Al Qaeda took no chances with the English brothers’ safety. They received much of their training behind mud-brick walls in the sprawling compounds that are typical of Pakistan’s tribal areas. The idea was to keep the men hidden from U.S. and Pakistani reconnaissance planes. Farooqi says the recruits were taught a wide variety of subjects, from religious and ideological doctrine to the art of molding, assembling and detonating state-of-the-art Iraqi-style shaped-charge IEDs. They learned how to make and use suicide-bomb vests, how to rig car bombs, how to motivate other men to sacrifice their lives for the jihad and how to maintain communications with Al Qaeda on the Afghan-Pakistani frontier. They’re not meant to be suicide bombers themselves, Farooqi says; they are far too valuable to waste.

Because Brits are normally granted temporary visas without having to apply in advance, any of them could enter the United States without a hitch unless they’re on a watch list. Newsweek actually has a photo of one of the “English brothers” inside the camp. How they managed that, I can’t possibly imagine.

Well, actually, sure I can.

The French are also worried, in part because Zawahiri apparently threatened them again in his latest tape. Remember how he announced that AQ had formed an alliance with an Algerian terrorist group? Turns out France has arrested 76 members of the group in connection with three separate plots — in the last 18 months alone.