If you really want to get into it, Port Security is a joke period. 2% of containers get inspected. TWO PERCENT. Whether or not it's an American, or British or UAE compant managing the port is moot. The containers are still loaded in foreign ports.
Its physically impossible to inspect every container coming to the US, and frankly way too late if a bomb does get loaded on a ship, and is detonated before it is even subject to a 2% chance of being inspected.
The only good and sane defense in this case is a good offense, which is just another reason why Islamist terrorism needs to be taken on overseas.