	Introduction

		Issue for Congress

This report provides background information and issues for Congress on three new ship-based weapons being developed by the Navy—solid state lasers (SSLs), the electromagnetic railgun (EMRG), and the gun-launched guided projectile (GLGP), also known as the hypervelocity projectile (HVP)—that could substantially improve the ability of Navy surface ships to defend themselves against surface craft, unmanned aerial vehicles (UAVs), and eventually anti-ship cruise missiles (ASCMs). The issue for Congress is whether to approve, reject, or modify the Navy's acquisition strategies and funding requests for these three potential new weapons. In particular for the Navy and Marine Corps, EMRG could provide the Navy with a new naval surface fire support (NSFS) weapon for attacking land targets in support of Marines or other friendly ground forces ashore. Earlier Developments Regarding Navy SSLs

Earlier developments in the Navy's efforts to develop high-energy SSLs include the following:
Between 2009 and 2012, the Navy successfully tested a prototype SSL called the Laser Weapon System (LaWS) against UAVs in a series of engagements that took place initially on land and subsequently on a Navy ship at sea. Current Navy SSL Development Efforts

The Navy is now developing SSLs with improved capability for countering surface craft and UAVs, and eventually a capability for countering ASCMs. Navy efforts to develop these more capable lasers include
the Solid State Laser Technology Maturation (SSL-TM) effort; the Ruggedized High Energy Laser (RHEL); the Optical Dazzling Interdictor, Navy (ODIN); the Surface Navy Laser Weapon System (SNLWS) Increment 1, also known as the high-energy laser with integrated optical dazzler and surveillance (HELIOS); and the High Energy Laser Counter-ASCM Program (HELCAP). As shown in Figure 3 , the Navy refers to the first four efforts above collectively as the Navy Laser Family of Systems (NFLoS). As also shown in Figure 3 , under the Navy's laser development approach, NFLOS and HELCAP, along with technologies developed by other parts of DOD, are to support the development of future, more capable lasers referred to as SNLWS Increment 2 and SNLWS Increment 3. When fired from a power gun, the projectile flies quickly, but not as quickly as it does when fired from EMRG. One advantage of GLGP is that the 5-inch and 155mm guns from which it would be fired are already installed on Navy cruisers and destroyers, creating a potential for rapidly proliferating GLGP through the cruiser-destroyer force, once development of GLGP is complete and the weapon has been integrated into cruiser and destroyer combat systems. Will the kinds of surface ships that the Navy plans to procure in coming years have sufficient space, weight, electrical power, and cooling capability to take full advantage of SNLWS and EMRG?
Three new ship-based weapons being developed by the Navy—solid state lasers (SSLs), the electromagnetic railgun (EMRG), and the gun-launched guided projectile (GLGP), also known as the hypervelocity projectile (HVP)—could substantially improve the ability of Navy surface ships to defend themselves against surface craft, unmanned aerial vehicles (UAVs), and eventually anti-ship cruise missiles (ASCMs).
The Navy has been developing SSLs for several years, and in 2014 installed on a Navy ship a prototype SSL called the Laser Weapon System (LaWS) that was capable of countering surface craft and UAVs. The Navy is now developing SSLs with improved capability for countering surface craft and UAVs, and eventually a capability for countering ASCMs. Navy efforts to develop these more capable lasers include
the Solid State Laser Technology Maturation (SSL-TM) effort; the Ruggedized High Energy Laser (RHEL); the Optical Dazzling Interdictor, Navy (ODIN); the Surface Navy Laser Weapon System (SNLWS) Increment 1, also known as the high-energy laser with integrated optical dazzler and surveillance (HELIOS); and the High Energy Laser Counter-ASCM Program (HELCAP).
The Navy refers to the first four efforts above collectively as the Navy Laser Family of Systems (NFLoS). Under the Navy's laser development approach, NFLOS and HELCAP, along with technologies developed by other parts of DOD, are to support the development of future, more capable shipboard lasers.
The Navy has been developing EMRG for several years. It was originally conceived as a naval surface fire support (NSFS) weapon for supporting Marines and other friendly forces ashore. Subsequently, it was determined that ERGM could also be used for air and missile defense, which strengthened interest in ERGM development. More recently, it was determined that the projectile to be fired by ERGM could also be fired by existing powder-propellant guns, including 5-inch and 155 mm guns on Navy cruisers and destroyers, and 155 mm artillery guns operated by the Army and Marine Corps. When fired from power guns, the projectile does not fly as quickly as it does when fired from an ERGM, but it still flies quickly enough to be of use as an air-defense weapon. The concept of firing the projectile from powder guns is referred to as GLGP and HVP. One potential advantage of HVP/GLGP is that, once developed, it can be rapidly deployed on Navy cruisers and destroyers and in Army and Marine Corps artillery units, because the powder guns in question already exist.
In addition to the question of whether to approve, reject, or modify the Navy's FY2020 funding requests for SSLs, ERGM, and HVP/GLGP, issues for Congress include the following:
whether the Navy is moving too quickly, too slowly, or at about the right speed in its efforts to develop these weapons; the Navy's plans for transitioning these weapons from development to procurement and fielding aboard Navy ships; and whether Navy the Navy's shipbuilding plans include ships with appropriate amounts of space, weight, electrical power, and cooling capacity to accommodate these weapons.