base used by usairmen. peter newman is a professor of security studies with kickngs london college. we keep hearing that there is no specific threat out there. but there is obviously enough buzz to worry folks here in the united states, even force them to cancel these events in england. what are you hearing about all of this? >> i think the background is the height ened threat since last year isis changed its strategy and it is calling on people on its enthusiastic supporters in the west to strike out and to do stuff. and ever since we've seen attacks in sidney and in copenhagen, in paris. all these people were not necessarily formally affiliated with the islamic state. they were enthusiastic supporters. they did stuff on their own and i guess that's the fear right now. that makes it so difficult and