The current and planned size and composition of the Navy, the rate of Navy ship procurement, and the prospective affordability of the Navy's shipbuilding plans have been oversight matters for the congressional defense committees for many years. On December 15, 2016, the Navy released a new force-structure goal that calls for achieving and maintaining a fleet of 355 ships of certain types and numbers. Key points about this new 355-ship force-level goal include the following: -- The 355-ship force-level goal is the result of a new Force Structure Assessment (FSA) conducted by the Navy. An FSA is an analysis in which the Navy solicits inputs from U.S. regional combatant commanders (CCDRs) regarding the types and amounts of Navy capabilities that CCDRs deem necessary for implementing the Navy's portion of the national military strategy, and then translates those CCDR inputs into required numbers of ships, using current and projected Navy ship types. The analysis takes into account Navy capabilities for both warfighting and day-to-day forward-deployed presence. The Navy conducts an FSA every few years, as circumstances require, to determine its force-structure goal. -- The new 355-ship force-level goal replaces a 308-ship force-level goal that the Navy released in March 2015. The actual size of the Navy in recent years has generally been between 270 and 290 ships. -- The figure of 355 ships appears close to an objective of building toward a fleet of 350 ships that was announced by the Trump campaign organization during the 2016 presidential election campaign. The 355-ship goal, however, reflects the national security strategy and national military strategy that were in place in 2016 (i.e., the Obama Administration's national security strategy and national military strategy). A January 27, 2017, national security presidential memorandum on rebuilding the U.S. armed forces signed by President Trump states: "Upon transmission of a new National Security Strategy to Congress, the Secretary [of Defense] shall produce a National Defense Strategy (NDS). The goal of the NDS shall be to give the President and the Secretary maximum strategic flexibility and to determine the force structure necessary to meet requirements." -- Although the 355-ship plan includes 47 more ships than the previous 308-ship plan, CRS notionally estimates that achieving and maintaining the 355-ship fleet could require adding 57 to 67 ships, including 19 attack submarines and 23 large surface combatants, to the Navy's FY2017 30-year shipbuilding plan, unless the Navy extends the service lives of existing ships beyond currently planned figures and/or reactivates recently retired ships. -- CRS estimates that procuring the 57 to 67 ships that might need to be added the 30-year shipbuilding plan to achieve and maintain a 355-ship fleet - a total that equates an average of about 1.9 to 2.2 additional ships per year over the 30-year period - could cost an average of roughly $4.6 billion to $5.1 billion per year in additional shipbuilding funds over the 30-year period, using today's shipbuilding costs. These additional shipbuilding funds are only a fraction of the total additional cost that would be needed to achieve and maintain a 355-ship fleet instead of 308-ship fleet. -- If defense spending in coming years is not increased above the caps established in the Budget Control Act of 2011, or BCA (S. 365/P.L. 112-25 of August 2, 2011), as amended, achieving and maintaining a 355-ship fleet could require reducing funding levels for other DOD programs. -- Navy officials have stated that, in general, the shipbuilding industrial base has the capacity to take on the additional shipbuilding work needed to achieve and maintain a 355-ship fleet, and that building toward the 355-ship goal sooner rather than later would be facilitated by ramping up production of existing ship designs rather than developing and then starting production of new designs.