I don’t know what all goes on today, but in my Army days the Army had its own navy. Yes, I even had a ride on one of their ships way back in 1974. And I also recall Army ships supplying an Army garrison in Ethiopia on the Red Sea.
There’s duplication all over the place.
https://en.wikipedia.org/wiki/List_of_ships_of_the_United_States_Army#Currently_active_ship_classes
“During World War II, the U.S. Army operated about 127,800 watercraft of various types.[1] Those included large troop and cargo transport ships that were Army-owned hulls, vessels allocated by the War Shipping Administration, bareboat charters, and time charters. In addition to the transports, the Army fleet included specialized types. Those included vessels not related to transport such as mine warfare vessels, waterway or port maintenance ships, and other service craft.”
“For example:[1]
Troop and cargo ships over 1,000 gross tons that often carried the U.S. Army Transport ship prefix “USAT” with their name if they were Army owned or bareboat chartered: 1,557 ships
Other ships over 1,000 gross tons, including hospital ships (prefix “USAHS”), cable ships, aircraft repair ships, port repair ships and others without any title other than “U.S. Army” and a number or name: 108 ships
Vessels under 1,000 gross tons of numerous types that include the 511 FS (”Freight and Supply”) small nonstandard coastal freighters of numerous designs, 361 minecraft with the large Mine Planters carrying U.S. Army Mine Planter (prefix “USAMP”) with a number above a name, 4,343 tugs of all types and a varied array of 4,697 launches and small service craft just designated U.S. Army with a number or name: 12,379
Barges and non-propelled watercraft that included 16,787 pontoons: 25,383
Amphibious assault craft: 88,366”
The Army still maintains a sizable navy.
The U.S. Army Has a Pretty Well-Kept Secret: It Has Its Own Navy
Made up of “army mariners” instead of sailors, here’s how the Army’s navy stacks up against foreign navies.
https://www.popularmechanics.com/military/navy-ships/a45690242/us-army-has-its-own-navy/