Risk / benefit
Personally, I don't think this bombing would pass a risk / benefit analysis for a covert operation.
Of course, such things have been done, and not just by the U.S.. The British government had the hold of the Lusitania (an armed and armored cruiser disguised as a passenger ship) filled with munitions, had all American passengers transfered to that ship, used political pressure to hold up publication of a full page warning by the German Government, and ordered the captain of the Lusitania to change course to pass directly in front of a known Uboat to be torpedoed, with great loss of American lives.
Evidence of the course change messages was erased (except at one relay station that erased the message text but left recorded the times, dates and Lusitania destination). The captain was put on trial for neglegence, but the judge eventually realized it was a fix and acquited him. That judge was banished from the bench by the British Crown.
The British government, presented with the evidence, officially admitted most details of the operation back in the '70s.
