From Fox News:

Morten Storm, who, as an informant for Denmark’s national intelligence agency Security and Intelligence Service (PET), had first-hand dealings with Anwar Al-Awlaki while the U.S.-born cleric was head of Al Qaeda in the Arabian Peninsula, said western countries must  protect themselves by canceling the citizenships of homegrown radicals who travel to the Middle East to fight or train. Once radicalized, homegrown jihadists can easily blend into society until given the signal to strike, he said.

“Deception is their warfare,” Storm said on a conference call facilitated by the New York-based terrorism research group Clarion Project. “One of the things that these groups believe in is that you are allowed to trick someone into believing that you stand for something else when you really have other agendas. They will act as normal members of western society.”