President Donald Trump and Navy leaders say the nation needs about 350 ships, roughly 75 more ships than the fleet has today.
But there isn't money in the defense budget to buy a lot of new ships at once, and they take years to build.
Adm. John Richardson, the chief of naval operations, says they could get closer to the target faster by counting unmanned vessels with capabilities similar to a manned ship — a new twist on the definition of a ship.
Unmanned undersea vehicles currently used by the Navy aren't at the point now where they could replace manned platforms. Richardson brought senior officers to Newport, Rhode Island, this month to talk about accelerating their development.
Richardson says the future Navy is going to be very different from today's fleet.