A shipped flagged for the Marshall Islands is effectively a US flagged ship due to the Compact of Free Association in which defense matters of the Marshal Islands are administrated by the US.
http://en.wikipedia.org/wiki/Compact_of_Free_Association
The US will absolutely be responsible for recovering this ship and her crew from the Iranians.
The US should be involved in the ship and crew recovery. So should a lot of countries.
There are a lot of countries who flag their ships in the Marshall islands, Monrovia, panama among other places. This is not a US flagged ship. There are thousands of ships flagged there from countries all around the world.
Be interesting to see how Obie dodges responsibility in this matter.
I went to your wiki on Compact of Free Assoc. and moved on to another wiki site. I think I can guess now why Obama referred to something like 56 or 57 states a while back. Among others there are Federated States of Micronesia, Republic of Marshall Islands, Republic of Palau, American Samoa, Guam, Northern Mariana Islands. Then there is also Puerto Rico, the Virgin Islands, and Washington, DC. Depending on the year, there are various numbers of associated places. Having gone to school in Indonesia and Hawaii, who knows what he was being taught or how outdated the textbooks. Patsy Mink, congresswoman from Hawaii, was fighting for the rights of some of these islands in the 1970s. At any rate it’s complicated.
http://en.wikipedia.org/wiki/Territories_of_the_United_States