The US Navy will convert four of its older Trident submarines to carrying the Trident-D5 missile. The Alaska, Jackson, Nevada, and Alabama currently carry the older Trident-C4. The Navy will buy an extra 65 Trident-D5 missiles in order to provide them for the converted subs. That will leave all of the remaining Trident subs carrying the D5, simplifying maintenance, training, and operations. --Stephen V Cole
