was $22.5 billion. History Background and funding Many of the features were developed under the DD-21 program ("21st Century Destroyer"), which was originally designed around the Vertical Gun for Advanced Ships (VGAS). In 2001, Congress cut the DD-21 program by half as part of the SC21 program; to save it, the acquisition program was renamed DD(X) and heavily reworked. Originally, the Navy had hoped to build 32 destroyers. That number was reduced to 24, then to 7, due to the high cost of new and experimental technologies. On 23 November 2005, the Defense Acquisition Board approved a plan for simultaneous construction of the first two ships at Northrop Grumman's Ingalls yard in Pascagoula, Mississippi, and General Dynamics' Bath Iron Works in Bath, Maine. However, at that date, funding had yet to be authorized by Congress. In late December 2005, the House and Senate agreed to continue funding the program. The U.S. House of Representatives allotted the Navy only enough money to begin construction on one destroyer as a "technology demonstrator". The initial funding allocation was included in the National Defense Authorization Act of 2007. However, this was increased to two ships by the 2007 appropriations bill approved in September 2006, which allotted US$2.568 billion to the DDG-1000 program. On 31 July 2008, U.S. Navy acquisition officials told Congress that the service needed to purchase more s and no longer needed the next-generation DDG-1000 class; only the two approved destroyers would be built. The Navy said the world threat picture had changed in such a way that it made more sense to build at least eight more Burkes rather than DDG-1000s. The Navy concluded from fifteen classified intelligence reports that the DDG-1000s would be vulnerable to forms of missile attacks. Many Congressional subcommittee members questioned that the Navy completed such a sweeping re-evaluation of the world threat picture in just a few weeks, after spending some 13 years and $10 billion on the development of the surface ship program known as DD-21, then DD(X), and finally DDG-1000. Subsequently, Chief of Naval Operations Gary Roughead cited the need to provide area air defense and specific new threats such as ballistic missiles and the possession of anti-ship missiles by groups such as Hezbollah. The mooted structural problems have not been discussed in public. Navy Secretary Donald Winter said on 4 September, "Making certain that we have—I'll just say, a destroyer—in the '09 budget