Britain is virtually certain to be attacked by terrorists inspired by the Somali terrorist group al-Shabaab, according to the agency charged with countering covert threats to British security. MI5 Director General Jonathan Evans said Thursday that "a significant number of UK [United Kingdom] residents" were training in al-Shabaab camps in Somalia.

Independent experts have indicated that the number of British residents involved is currently in the "tens," but could grow to more than 100 in the next year or two. Evans said al-Shabaab's recruiting campaign "shows many of the characteristics that made Afghanistan so dangerous as a seedbed for terrorism in the period before the fall of the Taliban."

"I am concerned that it is only a matter of time before we see terrorism on our streets inspired by those who are today fighting alongside al-Shabaab," Evans added.

Al-Shabaab's leadership has made no secret of its global jihadist goals and its admiration for al Qaida. One of al-Shabaab's senior military leaders, an American citizen named Omar Hammami (AKA Abu Mansoor al-Amriki) has criticized some Somali radicals for having limited territorial goals, while by contrast al-Shabaab "had a global goal including the establishment of the Islamic Khilaafah [caliphate] in all parts of the world."

Hammami also discussed the organization's religious methodology, likening it to that of senior al Qaida terrorists like Osama bin-Laden and Abu Musab Zarqawi. Saleh Ali Saleh Nabhan, al-Shabaab's now-deceased military commander, and Fazul Abdullah Mohammed, al-Shabaab's intelligence chief, have vowed to join bin Laden's global jihad.

"All of us are willing to obey his commands," Hammami said of bin Laden. Asked by the New York Times if he considered America a legitimate target for attack, Hammami replied: "It's quite obvious that I believe America is a target."