WASHINGTON — The U.S. Navy added a pair of littoral combat ships to the fleet, accepting delivery of the Sioux City and the Wichita during a Wednesday ceremony at Fincantieri’s Marinette Marine shipyard.

The ships, the sixth and seventh of Lockheed Martin’s monohulled Freedom-variant LCS, will commission later this fall and are destined to be based in Mayport, Florida, as part of LCS Squadron Two.

Over the next few years, the Navy will start accepting littoral combat ships at a fever pitch as the fleet builds up to the programmed 32 hulls, and likely more depending on the outcome of this year’s appropriations process in Congress. With the acceptance of Sioux City and Wichita, the Navy has 15 LCS in its inventory.

The rapid buildup of the fleet also puts pressure on the surface warfare community to get its newly reorganized LCS program up and running. Vice Adm. Richard Brown, head of Naval Surface Force Pacific, told Defense News in mid-August that four ships will be available for deployments in 2019, and that the community was finalizing the advanced predeployment training for the crews.

As for Marinette, the shipbuilder is making rapid progress on several other LCS. The Indianapolis, St. Louis, Minneapolis-Saint Paul, and Cooperstown are all under construction. The shipbuilder has also begun fabrication of the future LCS Marinette. The future Nantucket will begin fabrication in the fall.

Across the program, 29 LCS have been awarded, with 15 delivered to the Navy, 11 in various stages of construction and three in preproduction states, according to a release from Naval Sea Systems Command.

The Senate is currently weighing whether to appropriate two new LCS in 2019, one more than the Navy asked for in its budget — a proposition that drew a strong objection from the White House.

President Donald Trump’s budget director, Mick Mulvaney, said in a letter that one LCS, combined with the ships already in the pipeline, would keep both Marinette and Independence-variant shipbuilder Austal USA, based in Mobile, Alabama, afloat while the Navy switches gears to its new frigate program.