On Sept. 7, 2016, Donald Trump made a specific promise to an audience at the Philadelphia shipyards: “to build a Navy of 350 surface ships and submarines.” On March 2, Trump, now president, added to the specificity of that pledge by promising to increase the number of aircraft carriers to 12. The White House budget unveiled Monday breaks both of these promises. It’s a big deal to walk on this pledge, which is why, if the president does not correct his error, Congress should reject the budget and substitute its own plan.

A 350-ship fleet is key for both national security and international stability. China is rapidly growing its navy to fill the gaps left by Obama-era cutbacks to the current level of 274 ships. Reversing those cuts is crucial to preserving American supremacy at sea and supporting allies around the world. And Navy shipbuilding also can be a great jobs program: real jobs in real shipyards producing real ships to meet real threats.

The president’s budget has forgotten these benefits. Breaking Defense’s Sydney J. Freedberg Jr. summed up the details: “Despite his campaign pledge of a 350-ship fleet, President Trump’s first budget cuts Navy shipbuilding and aircraft procurement below what was enacted in 2017, documents released [Monday] reveal. Despite Trump’s criticism of President Obama’s defense plans, this budget sticks with Obama’s shipbuilding plan for 2018: eight ships. And it actually buys eight fewer aircraft than Obama planned.”

The budget includes a few excuses for Trump breaking his pledge: The Pentagon has to do a strategic assessment first, and readiness funds were more critical. It’s true that the readiness funding was needed, as were the missile defense funding and personnel expenditures, but these explanations still barely reach fig-leaf status.

(Jenny Starrs/The Washington Post)

But Office of Management and Budget Director Mick Mulvaney was always a skeptic on defense spending, and now he’s undercut the president’s crucial promises. With this budget there is no way to get the 350 ships the president promised by 2024, and it is very unlikely that a 12th carrier — if it remains authorized and is fully funded — will be in the fleet by 2027, long after the president leaves office even if he wins a second term.

There are plenty of superb plans on how to reach 350 ships by 2024, including one laid out in April by Jerry Hendrix, a retired Navy captain, and Robert C. O’Brien, a foreign policy adviser to multiple GOP candidates and a once and perhaps future candidate for Navy secretary. Both are friends and O’Brien a law partner of mine, but what matters most are the details proving that getting to 350 can be done — and done quickly.

Of course, neither the president nor the Navy needs to buy into the Hendrix-O’Brien plan, but a presidential promise needs a presidential plan, one Trump has reviewed and initialed, with the mix of ships specified, shipyards identified and construction schedules detailed. The president is above all a developer; developers understand critical paths and why every successful project depends on one. There is currently no plan for reaching 350 ships, eight months after Trump made that promise.

There isn’t a new secretary of the Navy either, which is perhaps one of the reasons the Navy got rolled in both the omnibus spending bill that kept the government going and the 2018 budget sent to Congress. The Navy needs a cheerleader. It needs another John Lehman, who helped make President Ronald Reagan’s goal of a 600-ship Navy a reality. And if Trump needed any incentive beside national security and his commitment to keeping campaign promises, he should realize that Teddy Roosevelt and Reagan are both known for the navies they built.

This budget betrays both the promise and the reality of a rebuilt fleet. And for what? And against what background? No political or policy goals are advanced by this skulduggery, and much is damaged thereby. Trump made six core promises in the campaign: A Supreme Court nominee in the mold of Justice Antonin Scalia (check), a border wall (on hold), repeal and replacement of Obamacare and tax reform (in progress), an infrastructure program and a 350-ship Navy (both abandoned by this budget). Many if not most of the “reluctant Trump” voters came home to him because of these promises. To break any one of them is taking a grave risk.

Further, to “provide for the common defense” is one of the very few specific purposes laid out in the Constitution’s preamble. This budget breaks the president’s commitment to do that in full, a breach from which recovery of credibility of defense spending promises will be difficult to recover.

When the president returns from his very successful trip abroad, he needs to nominate a Navy secretary and send Congress an addendum to his budget, one with a plan to keep his promises, and the funding to make that plan a reality. If he doesn’t, then the House and the Senate will have to save the president from his own OMB director and fund the 350-ship fleet the country needs.