A strong Navy is sunk, not buoyed, by excessive nuclear capability.

National security in the 21st century will require a strong economy and smart investments for national defense. Some in Congress want to violate both principles with a proposal to block retirement of excess nuclear-armed submarines.  It’s up to Congress as a whole to determine whether to use its defense dollars to counter the threats on the horizon or overfund the strategies of the past.

The Navy plans to replace its fleet of Ohio-class ballistic missile submarines over the next 30 years. With procurement of new subs lagging slightly behind planned retirements of the subs in service, the Navy expects the number of subs in service to dip from 12 to 10 for most of the 2030s.

On the challenge of fielding a smaller fleet, Chief of Naval Operations Adm. Jonathan Greenert testified before the Senate Armed Services Committee, saying, “We think that we can mitigate that risk.” Some in Congress think otherwise. The House Armed Services Committee  is proposing to prohibit the Navy from having fewer than 12 ballistic missile submarines in service.

The Navy plans to deploy about 1,000 warheads on its subs, in accordance with New START limits. How does the proposed mandated 12-sub fleet measure up? Such a fleet — capable of deploying 1,536 to 2,304 warheads — would far exceed our strategic needs. To put that in perspective, that is more warheads than Russia has in its entire deployed strategic arsenal.

As Lt. Gen. Dirk Jameson recently wrote, “Having more nuclear weapons doesn’t mean we are ‘winning’ — or will even succeed in deterring others from pursuing them. It merely reflects that our strategy is ill-suited to our times.”

We can defend our national security interests and those of our allies with fewer nuclear-armed submarines. Analyst Tom Collina has shown that a fleet of eight submarines — Ohio-class or its replacement — would allow the Navy to meet its planned deterrence mission. A rigid requirement for 12 nuclear-armed submarines is simply out of touch with today’s strategic realities. It’s also costly.

This proposal would keep older subs in the water for longer than necessary, pushing the limits of their expected service lives. Worse, if the U.S. military were to determine it needs fewer subs to meet its nuclear deterrence mission, the Navy will be forced to retain or possibly buy more subs than required.

With defense budgets tipping downward, the military cannot afford to spend billions of dollars on wasting nuclear assets.

As former Secretary of Defense Robert Gates pointed out  a year ago, every dollar spent on unneeded programs “is a dollar not available to support our troops and prepare for threats on the horizon.”

For the Navy, keeping unneeded nuclear subs would tax its operations budgets. If the Navy were required to buy excess new subs — costing $5 billion to $6 billion each — it would devour funds for modernizing the Navy’s surface fleet. Keep in mind that the Department of Defense expects to spend $350 billion to  acquire and operate the subs over the lifetime of the Ohio-replacement submarine program.

There will always be those in Congress who have not retired their Cold War glasses and argue for excessive subs, more warheads and more nuclear spending. But those arguments are unnecessary and unaffordable.

Benjamin Loehrke is a senior policy analyst at Ploughshares Fund.