They already had a rail gun that worked pretty well in the air defense roll.
http://www.onr.navy.mil/Media-Center/Fact-Sheets/Electromagnetic-Railgun.aspxWhat Is It?
The EM Railgun launcher is a long-range weapon that fires projectiles using electricity instead of chemical propellants. Magnetic fields created by high electrical currents accelerate a sliding metal conductor, or armature, between two rails to launch projectiles at 4,500 mph.
How Does It Work?
Electricity generated by the ship is stored over several seconds in the pulsed power system.
Next, an electric pulse is sent to the railgun, creating an electromagnetic force accelerating the projectile up to Mach 6.
Using its extreme speed on impact, the kinetic energy warhead eliminates the hazards of high explosives in the ship and unexploded ordnance on the battlefield.
What Will It Accomplish?
With its increased velocity and extended range, the EM Railgun will give Sailors a multi-mission capability, allowing them to conduct precise naval surface fire support or land strikes; ship defense; and surface warfare to deter enemy vessels.
Navy planners are targeting a 100+ nautical mile initial capability.
A variety of new and existing naval platforms are being studied for integration of a future tactical railgun system.
Here's the Laser
The U.S. Navy says its new laser weapon works and it will use it if it has to.
The Office of Naval Research reported Wednesday that its laser weapons system -- dubbed LaWS -- had performed flawlessly in tests aboard the amphibious transport dock USS Ponce in the Arabian Gulf from September to November.
"Laser weapons are powerful, affordable and will play a vital role in the future of naval combat operations," Rear Adm. Matthew L. Klunder, chief of naval research, said in a statement. "We ran this particular weapon, a prototype, through some extremely tough paces, and it locked on and destroyed the targets we designated with near-instantaneous lethality."
Klunder said the laser performed so well that the commander of the Ponce is now authorized to use it in defense of the vessel, according to a report from the U.S. Naval Institute.
"The captain of that ship has all of the authorities necessary if there was a threat inbound to that ship to protect our sailors and Marines (and) we would defend that ship with that laser system," Klunder is quoted as saying in a USNI report.
The laser could be used to stop threats ranging from drones and helicopters to small patrol boats, Klunder said, according to the USNI report.
Navy video released Wednesday shows the LaWS hitting exactly those types of targets. Watching the video, you can't see any light beam as you might expect from watching science fiction movies. Instead, the targets just burn up.
The Navy says the laser weapon is safer than conventional arms that use propellants and explosive warheads, and more cost-effective.
"At less than a dollar per shot, there's no question about the value LaWS provides," Klunder said in the Navy statement. "With affordability a serious concern for our defense budgets, this will more effectively manage resources to ensure our sailors and Marines are never in a fair fight."
The laser also takes fewer crew members to operate. It can be fired by one sailor using a video game-like controller.
The weapon performed without failure in conditions of high wind, humidity and temperature, the Navy said.
The Navy hopes to deploy variations of the laser weapon system in the fleet by 2020.