WASHINGTON - The US nuclear arsenal needs a multi-billion dollar overhaul in the coming decade to ensure the weapons' safety and effectiveness, defence officials said on Tuesday, despite warnings from arms control groups that the effort is unaffordable and unnecessary.
Assistant Defence Secretary Madelyn Creedon told a panel in the US House of Representatives that modernisation work on the aging weapons was needed to give policymakers the confidence they need to pursue President Barack Obama's goal of deeper cuts to the nuclear stockpile.
"Modernisation work of this kind is expensive, but there is no doubt that the investment ... is necessary," Ms Creedon told lawmakers examining a programme to reduce the number of warhead types for US nuclear bombs and to put guidance systems on the weapons.
"There is not a cost-effective alternative that meets the military requirements and policy objectives," she said, adding that the B61 gravity bomb, which is deployed in Europe, is a"cornerstone" of the US nuclear deterrence commitment to Nato.
The United States is currently at the start of what Air Force General Robert Kehler, the head of US Strategic Command, told the panel was a "multi-decade effort to recapitalise our nuclear deterrent force and its supporting infrastructure".
In addition to modernising 1970s-era weapons, in some cases replacing 1960s-model vacuum tubes with current-day electronics, the Pentagon plans to upgrade much of its so-called triad of delivery systems, including a new class of ballistic missile submarines and a new type of long-range bomber.
The non-partisan Stimson Centre think-tank last year estimated the total cost of the nuclear upgrade over the next decade, including weapons, infrastructure and delivery systems, at between US$350 billion (S$433.7 billion) and US$400 billion.
The plans, which call for increased nuclear outlays, come at a time when tight budgets are forcing the Pentagon to slash projected spending by nearly US$1 trillion over the next decade.
The modernisation effort has drawn criticism from arms control groups. The independent Union of Concerned Scientists said in a report last week the plans were misguided and violated the spirit of Obama's pledge not to develop new nuclear weapons.
Dr Kingston Reif, an analyst at the Centre for Arms Control and Non-Proliferation, said spending nearly US$11 billion to upgrade the B61 bomb at a time when tight budgets are forcing US military cuts is also unwise.
"That programme is unaffordable, unrealistic and unnecessary because there are cheaper alternatives to extend the life of the weapon," he said in an interview.
Mr Obama has endorsed the goal of a world without nuclear weapons and negotiated the "New START" treaty with Russia, which committed the former Cold War rivals to reducing deployed strategic nuclear weapons to 1,550 each by 2018.
The US leader said in a speech in Berlin this summer he had concluded he could further cut deployed US strategic weapons by a third, to between 1,000 and 1,100, and still guarantee US and allied security.
Officials responsible for the US arsenal told the House panel on Tuesday that to enable deeper cuts, officials needed to have complete confidence that existing weapons would work.
"There are physical processes occurring in these weapons that ... require that we execute this life extension program,"said Dr Paul Hommert, the director of Sandia National Laboratories, which is responsible for ensuring the arsenal is safe and reliable.