The U.S. Secretary of the Navy over the next 30 years wants to expand the American fleet from today’s 294 front-line ships to a staggering 435 ships.

Thomas Modly’s proposal, first reported by USNI News, doubles down on the Trump administration’s failing plan to grow the U.S. Navy to 355 ships. But Modly has not fully explained how the Navy can afford 420 front-line vessels when the service readily admits it cannot afford 355.

The likely result of this disconnect is fleet planning that, in fact, has no bearing on reality. In that case Congress, not the Navy, will determine the shape and size of the fleet through annual appropriations. Navy leaders’ proposals will become increasingly meaningless.

There’s precedent for this state of affairs. The U.S. Air Force for years has posited a vastly-expanded future force structure that it has made no effort actually to execute and which everyone knows is unaffordably under any projected budget.

Modly on Feb. 26, 2020 appeared before lawmakers to discuss his fleet plan. “I’m not sure 355 is the right number now,” Modly said, according to USNI News. “The number is like 435 with unmanned in there. It’s 390 without unmanned in there.”

Following the late-2019 collapse of the earlier 355-ship plan, the Navy repeatedly has delayed releasing detailed force-structure plans. Occasional and inconsistent testimony from a few senior leaders has replaced detailed, written planning. The service’s budget proposal for 2021 asks for the smallest number of ships of any budget in a decade.

The 435 manned vessels in Modly’s proposal would include fewer large ships such as today’s amphibious ships and Arleigh Burke-class destroyers and more smaller vessels such as the Littoral Combat Ship and the Navy’s future FFG(X) missile frigate.

The unmanned vessels Modly referred to include robotic surface ships and submarines. The Navy recently began small numbers of unmanned vessels for experiments. The sailing branch also wants a new, small amphibious ship and a new, small support vessel. Both of these types at present exist only on paper.

All these new ships would have to be dramatically cheaper than today’s ships are in order for the Navy to have any chance of expanding. Modly told lawmakers that the plan for a 355-ship fleet, which mostly included more copies of existing big ship types, would cost $12 billion to $13 billion a year on top of the roughly $20 billion Congress annually has given the Navy for new ships recently.

But such a huge spending boost is unrealistic. U.S. military spending is flattening, not growing, as deep tax cuts for corporations and the wealthy push annual federal budget deficits above a trillion dollars. The Trump administration has exacerbated the budget crisis by transferring funds from shipbuilding accounts in order to add a few miles to the politically-motivated program to build a wall on the southern U.S. border.

Modly is betting on new classes of small warships being inexpensive to build, maintain and man. But the Navy made that bet before during an earlier period of flattening budgets. In the 1990s, the fleet launched development of a new, small and cheap surface combatant with a minimal crew.

But as often happens in weapons programs, the so-called “streetfighter” concept evolved into a much larger, more complex and expensive ship than the Navy initially wanted. It became the Littoral Combat Ship, which at 3,000 tons of displacements and $600 million per copy is anything but small or cheap. Problems maintaining the LCSs forced the Navy to add sailors to the vessels, undercutting the type’s purported manpower savings.

And in the end, the LCS doesn’t work. It’s lightly-built, under-armed and inefficient. The Navy recently cut production from 55 copies to just 35 then asked Congress to let it retire four of the ships after they’d sailed for just a few years.

If LCS is Modly’s idea of the new, small ship of the future, his idea is a bad one. And his bigger fleet will exist only on paper.

In that case, the Navy will find company in the Air Force, which in 2018 proposed to grow from 312 front-line squadrons to 386 by the late 2020s. But the flying branch never made a serious effort to execute the plan. Indeed, it recently has proposed cutting the number of planes in its inventory in order to pay for new command-and-control software and other in-development technologies.

In the absence of serious planning by the Air Force, Congress has stepped in. Lawmakers routinely modify or cancel the Air Force’s plans for retiring certain plane types while also adding extra new planes on top of those the flying branch asks for.

In reality, Congress plans the Air Force’s force structure without a lot of input from military leaders. If Navy leaders can’t propose a shipbuilding plan that actually makes sense, and soon, it won’t be long before Congress plans the Navy’s force structure, too.

David Axe serves as Defense Editor of the National Interest. He is the author of the graphic novels  War Fix, War Is Boring and Machete Squad.