Kings Bay: Defense Secretary Chuck Hagel grabbed a ladder extending through the sleek black hull of the USS Tennessee at a Navy submarine base here and disappeared down the hatch for a close look at one of the Pentagon`s most daunting budget issues.
Inside the vessel, 24 tubes for launching nuclear ballistic missiles sliced through the submarine`s decks, with the crew`s bunks and Spartan living quarters packed in around them.
The Tennessee and 13 other Ohio-class submarines are critical elements of the US nuclear deterrent but the oldest has been in service for 33 years and the end of the fleet`s useful life of 42 years is in sight.
"My last ship was older than I was," one submariner told Hagel.
Ageing poses the same challenge across the entire US nuclear weapons complex. Warheads, bombs, submarines, missiles and bomber aircraft are all approaching the end of their service.
Over the next 30 years, Washington will have to overhaul or replace much of its nuclear arsenal, an effort experts say could cost as much as a trillion dollars.
The question is what is truly indispensable and how to pay for it.
The congressionally mandated National Defense Panel put it bluntly in a July review of the Pentagon’s defense plans, saying the effort to build a new triad of nuclear bombers, missiles and submarines was "unaffordable" under present budget constraints.
With a 2011 legislation setting forth a decade of budget spending cuts in place, analysts say the White House will ultimately have to delay some systems, trim others or find more money. Most likely it will have to do all three.
"The bill is coming due, and it’s a huge bill," said Frank Klotz, head of National Nuclear Security Administration, the Department of Energy agency that maintains the weapons.
He noted that many US nuclear weapons systems were built in the Reagan era three decades ago and Washington has not invested heavily in them since then. But while the cost is huge, it is a fraction of the Pentagon`s spending, he said, with the annual defense budget of about $500 billion translating into $15 trillion over three decades.
"The question we have to ask ourselves as a nation is: `Is this something which we need to invest in?` Obviously the view of this administration is, it is," Klotz said in an interview.
With nuclear-armed Russia and China increasingly assertive on the world stage and other nations pursuing nuclear ambitions, Washington still needs an effective deterrent and President Barack Obama supports the modernization effort.
However, critics say the administration`s programs are too ambitious, too expensive and out of sync with the president`s aims to further reduce the size of the US nuclear arsenal.
"The current plans would perpetuate a nuclear arsenal size and structure that clearly exceeds our deterrence requirements as defined by the president," said Daryl Kimball, head of the Arms Control Association advocacy group.
Obama`s National Security Council has begun a review looking at how to revamp nuclear forces without jeopardizing other national security priorities, officials and defense analysts said.
Its decisions, which could resolve some of the financial conflicts, will feed into the 2016 budget draft due to be presented around February next year. Analysts say it is one of Obama`s last opportunities to influence US nuclear arms policy, one of his top issues.
The submarine program highlights the challenges ahead.
During his visit to the USS Tennessee last July, Hagel reassured submariners the administration was committed to building a new group of ballistic missile submarines.
The Navy plans to spend $1.2 billion this year for initial research and development and hopes to begin building the new vessel in 2021. The problem is that by the mid-2020s it would be spending half its ship-building budget on a dozen submarines it hopes will never have to fire a missile, squeezing funding needed to expand its fleet elsewhere.
Admiral Jonathan Greenert, the chief of naval operations, and Navy Secretary Ray Mabus have urged Congress to take the project out of the Navy’s shipbuilding budget and to fund it some other way.
Representative Randy Forbes, who heads the seapower panel of the House Armed Services Committee, has proposed paying for the submarine by a creating a sea-based deterrence fund in the Defense Department budget and giving the Pentagon more flexibility in moving money around.
But the plan does not provide new money and Forbes said Congress should ultimately provide some extra funds.
Former Pentagon comptroller Robert Hale, however, warned that with several major weapons purchases going to full production next decade, the United States would still face big challenges to fund the systems it wants.
"We`re going to have to have overall debate over priorities," he told Reuters.
Arms control groups say nuclear overhaul plans simply need to be trimmed.
Kimball`s Arms Control Association released a study last week titled "The Unaffordable Arsenal" detailing cost-cutting steps, many recommended by government oversight panels.
The Congressional Budget Office, for example, has said Washington could save about $40 billion over 30 years by delaying the new submarine program by three years and buying only eight instead of the planned 12.
Deferring the long-range bomber program until after 2023 could cut $32 billion in new spending over the decade, freeing up money for other priorities, like the F-35 Joint Strike Fighter and new KC-46A refueling tankers, the CBO said.
All in all, savings could reach some $70 billion over the next 10 years, according to the "Unaffordable Arsenal" report. That would be 20 percent less than the $355 billion spending the CBO has projected for the decade based on Pentagon plans.
Jon Wolfsthal, a former director of non-proliferation for Obama`s National Security Council, said the administration needed to force the tradeoffs and compromises needed to put the nuclear arsenal overhaul on a more financially realistic path.
"Right now the services are saying these are all priorities, we have to have them all, we have to have them on these timelines ... because they`ve been given orders that say they must maintain a certain level of nuclear capability," he said.
With its interagency review, the National Security Council may be moving toward some sort of solution.
Assistant Secretary of Defense Andy Weber, the head of nuclear, chemical and biological defense programs, said some compromises, such as eliminating duplicate systems, should make it possible to maintain a nuclear triad over the long term.
For example, the government is investing heavily in the B61-12 gravity bomb as a refurbished weapon for the long-range bomber, so perhaps an air-launched cruise missile replacement will not be necessary, Weber told reporters last month.
"These are the kinds of questions that I think we`re examining."