If one wants to understand the reasons behind the great concerns of the U.S. over Iran and the Somalian pirates, he must understand the strategically important choke points of Strait of Hormuz, Persian Gulf, Gulf of Aden, and Red Sea.

See http://en.wikipedia.org/wiki/Strait_of_Hormuz
and
http://maps.google.ca/maps?sugexp=chrome,mod%3D0&qscrl=1&q=the+Strait+of+Hormuz&um=1&ie=UTF-8&hq=&hnear=0x3ef7184c25840e51:0x3d7b86ccdd367e5a,Strait+of+Hormuz&gl=ca&sa=X&ei=vPWFUP0Zk7_RAf6IgKAC&ved=0CJ8BELYD .