[svHyLyte]

Since when did USCG jurisdiction extend to the Persian Gulf?

The USCG, an arm of the military, has often been engaged in the business of protecting US Shipping, shipping routes whether in US waters or elsewhere including all of the areas where the United States has been dealing with hostilities. Compared with the US Navy, the Coast Guard is particularly skillful at operating in "thin" coastal waters and ports.

FWIW...