US vs Iran
Iran’s Guerrilla Fleet in the Persian Gulf
“In addition to a modest number of seagoing warships, including submarines, frigates, and large patrol vessels, as well a some amphibious ships and mine warfare vessels, the Iranian Navy, and the maritime wing of the Revolutionary Guard Corps, owns a substantial number small vessels. Not just the "official" small craft, but lots and lots of small boats that regularly carry guys with guns. No official numbers are given, but it appears that the Iranians have several thousand such small craft. These range in size from 23 foot long, motorized "Boston whalers," up to 65 feet long, 28-ton MIG-G-1900 patrol boats, with a few old American "Swift" boats thrown in. 
Over time and with enough ships US will be able to overcome these small vessels, but it will take time, and that time is something that the world economy can not afford.
Dr. Abbas Bakhtiar