The Obama Administration will be adding insult with its cancellation of production of the Navy’s Tomahawk and Hellfire missile programs. These decisions followed by just weeks the decision to reclassify two hospital ships, 10 coastal patrol craft and a ferry boat as “capital warships.”

The Tomahawk decision is particularly troubling, as the cruise missile has for years been the workhorse of presidents seeking to deliver limited, precise, stand-off military responses. During the 2011 Libyan crisis, the Navy flung 220 Tomahawks in support of operations. We launched more than 1,100 at Kosovo.

About 100 of these missiles are used in an average year. That means the Administration’s decision to stop production after 2015 will see the Navy’s stock of Tomahawks gone by around 2018. And disturbingly, there is no proven replacement in the development pipeline.

It appears that defense decisions are being driven more by budgetary concerns than policy or world events. The President has said his goal is to reduce defense spending to 2.9% of gross domestic product in 2017 from 4.6%; and to leave his successor a country stronger than the one he inherited. His goal is admirable; there is no more articulate defender of a strong military than the former chairman of the joint chiefs, Admiral Mullen, who has repeatedly said that the greatest threat to our country is our $17 trillion national debt.

Running out of ammunition and defining down what constitutes a warship is less a strategy than it is gimmickry. It appears to be driven by a sound-bite from the 2008 campaign — repeated just this week in the Daily Kos — that the American Navy is larger than the next 13 navies combined.

Indeed it is, and that is as it should be. America’s defense strategy is largely based on forward deployment of the Navy — both as a credible deterrent and as a force capable of projecting power. We don’t maintain large footprint military bases throughout the world. Unlike the Russians, whose annexation of Crimea gave it control of Ukraine’s main naval base and navy.

The accepted wisdom in some corridors appears to be that trimming a few ships here, reducing supply stockpiles there, and slowing down procurement, maintenance, and training are acceptable risks. Such assumptions are dangerous.

The world, after all, is a dangerous place; it refuses to cooperate with such wishful thinking. Plus, the Navy’s role is not simply to engage other navies on the high seas – the argument inherent in the “next 13 navies” political one-liner – but something far more diverse and demanding.

The Navy is still providing close air support to ground troops in Afghanistan. Just a few months ago, the chief of naval operations reported to Congress that the Navy was conducting about 30 missions a day; fully one-third of total close air support missions. Piracy is way down off Somalia – through the U.S.-led coalition efforts – but is on the rise along the west coast of Africa where Naval forces are spread much more thinly.

When North Korea’s Kim Jong-un announced ballistic missile tests last year, the Navy deployed two Aegis-equipped Navy warships to protect our allies. It will not be until 2015 that the American Army’s land based counterpart to Aegis — Thaad, for Terminal High Altitude Area Defense — arrives at Guam.

The Navy – and the nation – are proud of our responses to natural disaster and humanitarian crises. In 2013, when Typhoon Haiyan struck the Philippines, the Navy was able to deploy 50 ships and aircraft within hours – because we were forward deployed.

China is readying its first aircraft carrier for deployment; it is also fielding its first Jin-class nuclear ballistic missile submarine, and is engaged in aggressive posturing over the Senkaku Islands. Russia’s adventurism is unsettling; Egypt’s experiment with democracy is confusing; Iran is unpredictable; Syria is baffling; and Iraq is unstable. These developments don’t necessarily demand immediate responses, but they do require timely preparedness.

Unfortunately, that preparedness is being compromised. The CNO recently advised Congress that because of budgetary cutbacks, the Navy only has one carrier battle group and one amphibious ready group ready to “surge” – to get underway — within 30 days. This is down from three of each, just two years ago. And while we have ten aircraft carriers – and one more being built – only three are deployed. That is one of the reasons so many Tomahawks were thrown in the Libya operation: there were no aircraft carriers available.

Now the Administration is planning to “lay up” 11 guided missile cruisers – half of the Ticonderoga class fleet – in order to modernize them. But in a sleight-of-hand understandable to few outside Washington, there are no funds budgeted to re-man the renovated ships when they return from their renovations. This “should reduce costs,” said a senior Pentagon official who briefed reporters on the condition of anonymity.

It is part of the President’s 2015 budget proposal. A second decision –whether to request funds for the mid-life refurbishing and refueling of the nuclear aircraft carrier known as United States Ship George Washington – has been put off until the 2016 budget.

How much is enough to sustain an adequately sized, trained, and maintained Navy? More than is currently being budgeted. Under the current plan, our ability to join coalitions, lead them, or take independent action is compromised. A well-funded and prepared Navy offers our chief commander a powerful yet flexible tool with which to formulate and execute foreign policy. It is something no President should be without.

Mr. Cohen, an attorney at KDLM in New York, is a former Director of the United States Naval Institute.