However, since 2004 the United States has considered the group, which has lived for more than 25 years at a refugee camp in Iraq, "noncombatants" and "protected persons" under the Geneva Conventions.

CNN: Attack kills 5 at Iranian exile camp in Iraq

'But the second and I think most difficult one is the number of protected persons and whether we actually have, in the United Kingdom, sufficient capacity to actually have enough armed officers to do the job.

BBC: The Met has 2,600 firearms-trained officers