going forward, these are three separate cells, they're like needles in the proverbial haystack, they're difficult to find, even if you find them, in the west we can't arrest people for thought. if we think they might be up to something, that's not good enough. we have to have the resources to follow it before something like happened last night. >> we know there were seven people arrested in the manchester attack and 12 people after this attack. there was that other attack that happened on westminster bridge in march. what's going on in the united kingdom, all these attacks happening in such a close amount of time and multiple people involved? >> that's right. there's already been a surge in isis and inspired terrorist plotting in the uk. there have been five thwarted attacks, plots since the westminster attack.