From the Congressional Research Service May, 14 2013 Navy DDG-51 and DDG-1000 Destroyer Programs: Background and Issues for Congress:
As part of its action on the Navy’s FY2013 budget, Congress funded the procurement of three Arleigh Burke (DDG-51) class destroyers, or one more than the two that the Navy had requested for FY2013. The Navy is examining whether, following the March 1, 2013, sequester on Department of Defense (DOD) funding, the third DDG-51 will be executable with current funding. If the Navy determines that it is executable without additional funding, it would be built on a schedule similar to what would be executed for a ship fully funded in FY2014. If the Navy determines that it is not executable with current funding, Congress would have the option of providing additional funding for the ship in FY2014 to make it executable.
The Navy’s FY2014 budget submission calls for procuring nine Arleigh Burke (DDG-51) class destroyers in FY2014-FY2018, in annual quantities of 1-2-2-2-2. The three DDG-51s scheduled for procurement in FY2014-FY2015, and the first of the two scheduled for procurement in FY2016, are to be of the current Flight IIA design. The Navy wants to begin procuring a new version of the DDG-51 design, called the Flight III design, starting with the second of the two ships scheduled for procurement in FY2016. The four DDG-51s scheduled for procurement in FY2017-FY2018 are also to be of the Flight III design. The Flight III design is to feature a new and more capable radar called the Air and Missile Defense Radar (AMDR).