DARPA Looking at Ekranoplan

They are calling it the, "Liberty Lifter."

It appears rather similar to the Bartini Beriev VVA-14, developed by the Soviets in the 1960s and 1970s.

The basic idea is that by designing an aircraft that operates at low altitude, under 15m or so, you can take advantage of the ground effect to create increased efficiency.

The difference between the earlier early Ekranoplans and Liberty Lifter and the VVA-14 and is that while they are designed to operate at extremely low altitude, both of the latter are designed to be able to clime to altitude, something over 8,000m for the VVA-14, and 10,000m for the Liberty lifter, which allows the aircraft to avoid rough seas and inclement weather, albeit at the cost of reduced efficiency for that part of the flight:

DARPA has launched a new "Liberty Lifter" program to design, build and test a highly-efficient wing-in-ground effect aircraft for transporting "very large, heavy loads" over long distances without runways. Prototypes could fly as early as 2027.

The wing-in-ground effect has seen a bit of a mini revival over the last few years. There are a few players trying to get ground effect vehicles (GEVs) into commercial circulation – notably Singapore's Wigetworks, with its Airfish-8 and Boston's Regent, which has drawn in considerable funding and pre-sales to build a prototype of its fully electric, 12-passenger Viceroy seagliders.

All of these aircraft, as well as the Liberty Lifter and Russia's famous WW2 [This is incorrect.  The work on Ekranoplans began in the 1950s]  Ekranoplan program, aim to make use of a neat bit of physics: when a plane flies very close to the ground – at an altitude less than half of its own wingspan – it can ride on a cushion of high-pressure air between the wing and the surface, gaining additional lift while reducing lift-induced drag. This can make these things extremely efficient – flying at an altitude around 5 percent of the wingspan can get you from A to B up to 2.3 times more efficiently.

The real advantage of these aircraft is payload, with DARPA looking at payloads in excess of 1000 tons.

It really is remarkable how these concepts keep coming around.