"Movie night" is a time-honored tradition in the White House. For decades, US presidents have invited hand-picked guests of honor to the plush red screening room in their residence. Generally, the repertoire includes the latest blockbusters or old favorites like "Casablanca" or the "The Bridge on the River Kwai."

But US President Barack Obama often goes beyond the multiplex in choosing his fare. On Tuesday night, for example, he offered a real mood dampener: "Nuclear Tipping Point," a documentary film about the threat of nuclear terrorism -- and the dream of a nuclear weapons-free world.

He invited four gray-haired luminaries of the US security policy scene: former Secretaries of State Henry Kissinger and George Shultz, former Defense Secretary Bill Perry and Sam Nunn, a legendary arms expert and former senator. It was no coincidence, either: "Nuclear Tipping Point" is partly based on interviews with the quartet, who together have been fighting for years for the elimination of all nuclear weapons.

There was also no coincidence in the timing: On Tuesday, Obama presented the United States' new nuclear doctrine. The long-awaited, 72-page position paper represents the first step towards the implementation of a dramatic vision that Obama first spoke of one year ago on Prague's Charles Bridge. "I state clearly and with conviction America's commitment to seek the peace and security of a world without nuclear weapons," he said in his speech set against the picturesque backdrop.

As has happened with so many of Obama's promises, though, initially the only thing to come out of this was a compromise -- one that doesn't really satisfy anyone. His adopted motto: a little peace.

Break with the Past

Still, the so-called Nuclear Posture Review (NPR) could represent a break with the past. With his new doctrine, Obama is seeking to reduce the global nuclear threat by strongly and declaratively limiting, for the first time, the US prerogative, dating back to the Cold War, that Washington can deploy nuclear weapons against any country at any time. From now on, Washington has pledged to no longer threaten other countries -- at least those states that do not possess nuclear weapons and are signatories to the Nuclear Nonproliferation Treaty -- with a nuclear attack.

The new stance represents a renunciation of the view that the deterring power of nuclear weapons also keeps conventional opponents in their place. "Our nuclear arsenal also helps deter enemies from using chemical and biological weapons," Defense Secretary Robert Gates said as recently as October 2008, in a speech given at the Carnegie Endowment for International Peace. At the time, he was still serving under Obama's predecessor in the White House, George W. Bush. Now, however, the terms are to be stricter: Conventional weapons must be deployed against conventional threats, and the specter of nuclear weapons can only be raised against a nuclear threat.

That potential threat is limited to a relatively small group of nuclear powers -- many of which are allied with the US. According to the Federation of American Scientists, the list of countries includes, in addition to the US, the United Kingdom, Russia, France, China, India, Pakistan, North Korea and (though the government officially pursues a policy of ambiguity) Israel.

Obama Personally Edited Text

Reactions to Obama's nuclear shift were predictable. For some, the strategy isn't far-reaching enough. Paul Ingram, executive director of the British American Security Information Council, said the moves represented an "unconvincing balancing act," adding: "There's no real indication of the deep shifts in thinking necessary to begin giving up the nuclear fix."

Others, though, complain that the policy has no teeth. "The president's dream of a worldwide liberal utopia is going to undermine the security of the United States," Peter King, the top Republican on the House Committee on Homeland Security, said in an interview with the New York Post newspaper.

But this polarization also mirrors the internal debate between the Pentagon, State Department and White House. The discussions were so heated than the release of the White House nuclear review was delayed by four months. Finding a formulation that everyone could agree to ultimately required 102 meetings. The White House even consulted with Congress and foreign partners. And Obama reportedly took the step of personally editing the text himself on numerous occasions. One member of Obama's government described the process as having taken "darn near forever."

Responding to Changing Times

The fact remains, however, that as long as nuclear weapons exist, nuclear weapons will need to exist. It's true that the US has committed itself to not constructing any new warheads, a position that Obama apparently pushed through against the will of his own defense secretary. But the Americans are keeping their existing arsenal maintained and ready to use, even if in future they will think longer before pressing the button.

The new doctrine also takes into account the fact that times have changed. The Cold War between the former superpowers is over. Today's wars are very different and often involve non-state actors.

"The greatest threat to US and global security is no longer a nuclear exchange between nations," Obama said, "but nuclear terrorism by violent extremists and nuclear proliferation to an increasing number of states."

And no arsenal of warheads can protect against terrorists. "If terrorists get their hands on nuclear weapons or materials, and you don't even know their return address, we will be faced with a very dangerous moment," says former Secretary of State George Shultz in the film "Nuclear Tipping Point." "If you think of the people who are committing suicide attacks and people like that get a nuclear weapon, they are almost by definition not deterrable."

Will Doctrine Encourage Iran's Nuclear Activities?

But the new doctrine is a well-staged drum roll at the start of what a senior defense official, speaking at the presentation of the strategy, called a "busy nuclear season." On Thursday, Obama returns to Prague in order to sign the new START treaty on nuclear disarmament together with Russian President Dmitry Medvedev. Then, early next week, 46 heads of state and government will meet for a summit on nuclear security in Washington at Obama's invitation.

The doctrine is, of course, directed at two countries who will not be attending the summit: Iran and North Korea. Because the two states have violated various nuclear agreements, especially the nonproliferation treaties and UN Security Council resolutions, Washington is reserving the right of first use against those countries.

Experts doubt, however, whether the US's position will carry much weight with the regimes in Tehran and Pyongyang, especially given the fact that such assurances would mean little in the event of a nuclear Armageddon.

"No one knows what we might do in a crisis or war, so pledges of no-first-use are essentially meaningless," writes Harvard political scientist Stephen Walt on the Web site of the magazine Foreign Policy , where he mocks the NPR report as standing for "Nuclear Public Relations." "At best, this new statement will have little or no effect," he writes. "At worst, however, excluding Iran in this fashion -- which amounts to saying that Iran is still a nuclear target even when it has no weapons its own -- merely gives them additional incentives to pursue a nuclear weapons option." After all, a country that feels threatened wants to have a deterrent of its own.

Is Obama's doctrine counterproductive, in that case? "The administration has painted a nuclear target on Iran's back," Flynt Leverett of the New America Foundation think tank and Hillary Mann Leverett, head of the consulting firm Strategic Energy and Global Analysis, write in their Iran blog. 

'Reassurance to Allies'

European analysts, meanwhile, are likely to be critical of the lack of commitment in the review to withdrawing existing US warheads from the territory of America's allies. "Although the risk of nuclear attack against NATO members is at an historic low," the paper reads," the presence of US nuclear weapons (…) contributes to Alliance cohesion and provides reassurance to allies and partners who feel exposed to regional threats."

This sentence is likely to frustrate in particular German Foreign Minister Guido Westerwelle, who recently called for the withdrawal  of all US nuclear weapons from Europe. The Obama doctrine now places an obstacle in that path. "Any changes in NATO's nuclear posture should only be taken after a thorough review within -- and decision by -- the Alliance," the review states.

Hence Obama's doctrine does not solve the global dilemma about nuclear weapons. And that is something which the former Secretary of State Colin Powell, who guarded US nuclear weapons as a young soldier in Germany, knows very well. In the age of terror, Powell says in "Nuclear Tipping Point," the film that Obama showed in the White House on Tuesday, nuclear weapons are more of a threat than ever: "They must never be used."