The USS Michigan is one of four Ohio-class guided-missile submarines, originally designed to launch nuclear missiles, that were converted between 2003 and 2007 to be able to fire Tomahawk cruise missiles.
The USS Florida (SSGN 728) was converted in August 2003, the USS Michigan (SSGN 727) in October 2004, the USS Ohio (SSGN 726) in December 2005, and the USS Georgia (SSGN 729) in December 2007.
According to the U.S. Navy, “combined, the four SSGNs represent more than half of the Submarine Force’s vertical launch payload capacity with each SSGN capable of carrying up to 154 Tomahawk land-attack cruise missiles”. Additionally, the converted submarines can carry and deploy as many as 66 special operations personnel.
The four converted submarines can carry up to 616 tomahawk missiles, or over ten times the number launched on Syria earlier this month. Adding up to as 265 special operators, like Navy SEALs, and these sea going vessels are, according to the Navy, “land attack and SOF [Special Operation Forces] platforms.”