WASHINGTON (Reuters) - Whether it is Barack Obama or John McCain, the new U.S. president will take over one of the most awesome of responsibilities -- his finger will be on the trigger of the country’s huge nuclear arsenal.

People flash the sign of peace during a walk marking the anniversary of the Hiroshima atomic bombing in Kuala Lumpur August 6, 2005. . REUTERS/Bazuki Muhammad

In advance of the election, some of Washington’s most influential national security thinkers have argued for a dramatic shift in U.S. policy, to actively pursue the eventual elimination of all nuclear weapons from the Earth.

Many dismiss this goal as a dream, given the lack of trust among the nuclear weapons powers and the entrenched role that atomic weapons have in the global balance of power.

But Democratic front-runner Obama, who is leading in polls before Tuesday’s election, endorsed it and his Republican rival John McCain said he hopes to move to “the lowest possible number” of U.S. nuclear weapons.

“I will not authorize the development of new nuclear weapons,” Obama said in September. “And I will make the goal of eliminating nuclear weapons worldwide a central element of U.S. nuclear policy.”

The debate, which dates back to the early days of the Cold War, was revived around the start of the election campaign in January 2007 when four Washington national security heavyweights published a call for a total ban.

They were Henry Kissinger and George Shultz, who served as secretaries of state in Republican administrations, William Perry, who was Democratic President Bill Clinton’s defense secretary, and former Senate Armed Services Committee Chairman Sam Nunn, who has been advising Obama.

In 2008, they said their vision was supported by 14 more former top national security officials from recent administrations.

WORLD WITHOUT NUCLEAR WEAPONS

George Perkovich, director of the nonproliferation program at the Carnegie Endowment, says nuclear weapons can be banned even if they cannot be “disinvented” -- much like Nazi-style gas chambers.

“Those (gas chambers) haven’t been disinvented but we don’t have them around now and don’t think they should be around and we’re prepared to take action to enforce that,” he told a Washington audience last week.

“The next American president should emphasize the goal of a world without nuclear weapons -- and really mean it,” Perkovich said. Most nuclear weapons, which for many are a symbol of the Cold War, are still held by the United States and Russia.

President Ronald Reagan discussed the idea of a total abolition of the weapons in 1986 with Soviet leader Mikhail Gorbachev -- to the shock of some of their advisers.

The 1968 Nonproliferation Treaty obliged the five declared nuclear weapons states -- China, France, Russia, Britain and the United States -- to work toward disarmament.

India, Pakistan and North Korea have all since tested nuclear weapons and Israel is widely assumed to have them. The United States accuses Iran of wanting to build a bomb, although Iran says its nuclear program is for peaceful purposes.

In their January 2007 article in the Wall Street Journal, the four prominent figures noted a growing fear that non-state groups like al Qaeda could get their hands on a bomb -- and use it as the “ultimate means of mass devastation.”

But if the world had zero nukes, there would be none for either governments or non-state groups to acquire, they said.

REALISTIC PROPOSAL?

Some worry about how to reach such a goal given the perils for Washington of leading by giving up bombs when others, like Russia and China, are modernizing their stockpiles.

In the current edition of the journal “Foreign Affairs” two other U.S. experts say Washington must launch a vigorous diplomatic effort to convince the world of “the logic of zero.”

Ivo Daalder, senior fellow at the Brookings Institution and Jan Lodal, immediate past president of the Atlantic Council, say that a “remarkable” bipartisan consensus has grown around the idea. They said as part of the process Washington should reduce its arsenal to no more than 1,000 total weapons.

Defense Secretary Robert Gates last week said the United States should update its nuclear arsenal. But he added he would advise the next president to seek agreement with Russia on cuts in nuclear warheads below the limit of 1,700 to 2,200 deployed warheads in an existing treaty.

Gates noted that three past presidents he had worked for favored eliminating all nuclear weapons and said so publicly. They were Jimmy Carter; George Bush, the current president’s father; and Reagan.

But Gates said some efforts toward a nuclear weapons-free world had not been realistic.

“All have come up against the reality that as long as others have nuclear weapons, we must maintain some level of these weapons ourselves to deter potential adversaries and to reassure over two dozen allies and partners who rely on our nuclear umbrella for their security, making it unnecessary for them to develop their own,” he said.