Around half all terrorist cells operating in Britain originate from Pakistan, the British intelligence services believe.
Security experts suggest there are a large number of terrorist cells operating more or less independently across the Caucasus region.
He has not yet provided the detailed information needed to round up members of other cells operating in Southeast Asia, this official said.
Within the US, the Zetas' influence is widespread – cells operating across the country, distributing drugs, their contacts laundering money through established banks and other channels.
Since May the Saudis have broken up six to eight Qaeda cells operating within the country, including several in the past few weeks, Saudi and American officials said.
Mr. Cheema said that group was one of several militant groups with terrorist wings that had cells operating in the area of Bahawalpur, which lies in the Indus River valley about 600 miles south of Islamabad.
"The suspicion is that there are a number of sleeper cells operating on both sides of the Channel that have become radicalized and are looking to do some kind of attack," the BBC said.
Trévidic talks about "the porosity of the Franco-Belgian border" so far as cells operating in both countries are concerned – the axis between Paris and Brussels that has driven the wave of attacks since Charlie Hebdo.
Some analysts believe that Al Qaeda today is a model of what is called "leaderless resistance": self-appointed cells operating with help and inspiration from materials that they find online.
In all, prosecutors say, about 100 people are implicated in the case, with several cells operating under larger ones -- in some cases, one immigrant's trip from Central America to South Texas involved several intermediaries, one to help cross the Rio Grande, another to take the immigrant to a safe house, another to deliver food.
But law enforcement officials said Friday that they believed that Ms. Rice's testimony before the commission investigating the Sept. 11 attacks -- including her account of scores of F.B.I. investigations under way that summer into suspected Qaeda cells operating in the United States -- overstated the scope, thrust and intensity of activities by the F.B.I. within American borders.
