Deploy near US coast? Yeah, then what, Sparky?
Deploy nuclear mines? Wait until there is minimum coverage and then race into a port and detonate a nuclear bomb? (Do you think Obama would allow the Navy to sink a little boat just because it was heading towards a port? Remember courageous restraint!) Deploy regular mines that can be turned on by remote control? Gather electronic intelligence? Deploy and supply terrorist teams?
Remember, these arent the Soviets, who were led by a bunch of octogenarians only interested in maintaining their dachas and their status. These are people who dress their babies in bomb suits for party pictures. Dont expect rational thought from an apocalyptic culture that was born to bring jihad to the world so everybody they know could die in the glorious return of the 12th imam.
There are rumors that Iran has modified their Shahab-3 mobile IRBMs to launch from a freighter deck. If true, they won't have to race into port.