The Navy is developing three new ship-based weapons that could improve the ability of Navy surface ships to defend themselves against missiles, unmanned aerial vehicles (UAVs), and surface craft: the Surface Navy Laser Weapon System (SNLWS), the electromagnetic railgun (EMRG), and the gun-launched guided projectile (GLGP), previously known as the hypervelocity projectile (HVP). The Navy refers to the initial (i.e., Increment 1) version of SNLWS as HELIOS, an acronym meaning high-energy laser with integrated optical dazzler and surveillance. EMRG could additionally 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. The Department of Defense is exploring the potential for using GLGP across multiple U.S. military services. Any one of these three new weapons, if successfully developed and deployed, might be regarded as a "game changer" for defending Navy surface ships against enemy missiles and UAVs. If two or three of them are successfully developed and deployed, the result might be considered not just a game changer, but a revolution. Rarely has the Navy had so many potential new types of surface-ship air-defense weapons simultaneously available for development and potential deployment. Although the Navy in recent years has made considerable progress in developing technologies for these new weapons, a number of significant development challenges remain. Overcoming these challenges will require additional development work, and ultimate success in overcoming them is not guaranteed. The issue for Congress is whether to approve, reject, or modify the Navy's funding requests and proposed acquisition strategies for these three potential new weapons. Potential oversight questions for Congress include the following: Using currently available air-defense weapons, how well could Navy surface ships defend themselves in a combat scenario against an adversary such as China that has or could have large numbers of missiles and UAVs? How would this situation change if Navy surface ships in coming years were equipped with SNLWS, EMRG, GLGP, or some combination of these systems? How significant are the remaining development challenges for SNLWS, EMRG, and GLGP? Are current schedules for developing SNLWS, EMRG, and GLGP appropriate in relation to remaining development challenges and projected improvements in enemy missiles and UAVs? When does the Navy anticipate issuing roadmaps detailing its plans for procuring and installing production versions of SNLWS, EMRG, and GLGP on specific Navy ships by specific dates? 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? What changes, if any, would need to be made in Navy plans for procuring large surface combatants (i.e., destroyers and cruisers) or other Navy ships to take full advantage of SNLWS and EMRGs? Given the Navy's interest in HPV, how committed is the Navy to completing the development of EMRG and eventually deploying EMRGs on Navy ships? Are the funding line items for SNLWS, EMRG, and GLDP sufficiently visible for supporting congressional oversight?