I agree Patrick, this looks like a textbook building of a case against Iran.
Park the fleet nearby, wait for some lunatic extremists to try something futile, like a suicide bomb or actually planting something on one of the ships, which will be viewed as a national "attack" by Iran of course.
If some lunatic doesn't try something, they may just make it up, like our government did with Operation Northwoods in Cuba.
Operation Northwoods: Justification for U.S. Military Intervention in Cuba, 3/13/62
Yes, it could just be posturing by us, to try to use military show of force to Ahmidenajad(?) that we aren't messing around, but we should know by now those tactics don't do much but cause anger and more tension in tight situations in the missile age.