My fear is not only another Mumbai......but another Beslan with the terrorist detainees being sent to US soil.
Nah,
A nuke floated into New York harbor
in routine water traffic
Or,
Parking car bombs in hospitals or schools
Maybe,
Floating a houseboat against a dam
packed with high explosives
scuttle it, then detonate below water
That's what I would do
If I wanted to cause maximal terror
Pretty tough to stop