Tell that to the Germans. They managed to sink 56 ships in the Gulf during 1942 and 1943. The only sub we sank was the U-166, about 45 miles from the mouth of the Mississippi, not too far from where this rig exploded and sank.
Sure our ASW is much better now, but we don't have much, if any, in the Gulf. A small mini sub, like the North Koreans and Iranians have, could be carried as cargo (which we SHOULD have detected in route) to Cuba.
This is the Iranian model, carries mines or a torpedo.
With Guess Who doing an inspection
This is a google maps shot of the Bandar-e-Abbas naval base I see what appears to be six of the little forkers in the NE (upper right) section of the base, moored in 3 nests of 2 each.
It appears somewhat similar to the NK Sang-O class.
