The Zumwalt-class destroyer is a class of three United States Navy guided-missile destroyers designed as multi-mission stealth ships with a focus on land attack. It is a multi-role class that was designed with a primary role of naval gunfire support and secondary roles of surface warfare and anti-aircraft warfare. The class design emerged from the DD-21 "land attack destroyer" program as "DD(X)" and was intended to take the role of battleships in meeting a congressional mandate for naval fire support. The ship is designed around its two Advanced Gun Systems (AGS), turrets with 920 round magazines, and unique Long Range Land Attack Projectile (LRLAP) ammunition. LRLAP procurement was canceled, rendering the guns unusable, so the Navy re-purposed the ships for surface warfare. Starting in 2023, the Navy will remove the AGS from the ships and replace them with hypersonic missiles. These ships are classed as destroyers, but they are much larger than any other active destroyers or cruisers in the U.S. Navy. The vessels' distinctive appearance results from the design requirement for a low radar cross-section (RCS). The Zumwalt class has a wave-piercing tumblehome hull form whose sides slope inward above the waterline, dramatically reducing RCS by returning much less energy than a conventional flare hull form. The appearance has been compared to that of the historic USS Monitor and her famous antagonist CSS Virginia. The class has an integrated electric propulsion (IEP) system that can send electricity from its turbo-generators to the electric drive motors or weapons, the Total Ship Computing Environment Infrastructure (TSCEI), automated fire-fighting systems, and automated piping rupture isolation. The class is designed to require a smaller crew and to be less expensive to operate than comparable warships. The lead ship is named for Admiral Elmo Zumwalt and carries the hull number DDG-1000. Originally, 32 ships were planned, with $9.6 billion research and development costs spread across the class. As costs overran estimates, the quantity was reduced to 24, then to 7, and finally to 3. This significantly increased the cost per ship to $4.24 billion ($7.5 billion including R&D costs), well exceeding the per-unit cost of a nuclear-powered ($2.688 billion). In July 2008, the Navy requested that Congress stop procuring Zumwalts and revert to building more Arleigh Burke destroyers. This final cut in procurement led to a dramatic per-unit cost increase that eventually triggered a Nunn–McCurdy Amendment breach. In April 2016, the total program cost