In the depths of the cold war, in 1983, a senior at Columbia University wrote in a campus newsmagazine, Sundial, about the vision of "a nuclear free world." He railed against discussions of "first- versus second-strike capabilities" that "suit the military-industrial interests" with their "billion-dollar erector sets," and agitated for the elimination of global arsenals holding tens of thousands of deadly warheads.
The student was Barack Obama, and he was clearly trying to sort out his thoughts. In the conclusion, he denounced "the twisted logic of which we are a part today" and praised student efforts to realize "the possibility of a decent world." But his article, "Breaking the War Mentality," which only recently has been rediscovered, said little about how to achieve the utopian dream.
Twenty-six years later, the author, in his new job as president of the United States, has begun pushing for new global rules, treaties and alliances that he insists can establish a nuclear-free world.
"I'm not naïve," President Obama told a cheering throng in Prague this spring. "This goal will not be reached quickly - perhaps not in my lifetime. It will take patience and persistence."
Yet no previous American president has set out a step-by-step agenda for the eventual elimination of nuclear arms. Mr. Obama is starting relatively small, using a visit to Russia that starts Monday to advance an intense negotiation, with a treaty deadline of the year's end, to reduce the arsenals of the nuclear superpowers to roughly 1,500 warheads each, from about 2,200. In an interview on Saturday, Mr. Obama, conscious of his critics, stressed that "I've made clear that we will retain our deterrent capacity as long as there is a country with nuclear weapons."
But reducing arsenals, he insisted, would be the first step toward giving the United States and a growing body of allies the power to remake the nuclear world. Among the goals: halting weapons programs in North Korea and Iran, discouraging states from abandoning the Nuclear Nonproliferation Treaty and ending global production of fuel for nuclear arms, a step sure to upset Pakistan, India and Israel.
Even before those battles are joined, opposition is rising. "This is dangerous, wishful thinking," Senator Jon Kyl, Republican of Arizona, and Richard Perle, an architect of the Reagan-era nuclear buildup that appalled Mr. Obama as an undergraduate, wrote last week in The Wall Street Journal. They contend that Mr. Obama is, indeed, a naïf for assuming that "the nuclear ambitions of Kim Jong-il or Mahmoud Ahmadinejad would be curtailed or abandoned in response to reductions in the American and Russian deterrent forces."
In the interview, the president described his agenda as the best way to move forward in a turbulent world.
"It's naïve for us to think," he said, "that we can grow our nuclear stockpiles, the Russians continue to grow their nuclear stockpiles, and our allies grow their nuclear stockpiles, and that in that environment we're going to be able to pressure countries like Iran and North Korea not to pursue nuclear weapons themselves."
Realist or dreamer, Mr. Obama has an interest in global denuclearization that arises from what can best be described as a lost chapter of his life. Though he has written two memoirs, he has volunteered few details about his two years at Columbia.
"People assume he's a novice," said Michael L. Baron, who taught Mr. Obama in a Columbia seminar on international politics and American policy around the time he wrote the Sundial article. "He's been thinking about these issues for a long time. It's not like one of his advisers said, ‘Why don't you throw this out?' "
In a paper for Dr. Baron, Mr. Obama analyzed how a president might go about negotiating nuclear arms reductions with the Russians - exactly what he is seeking to do this week.
At critical junctures of Mr. Obama's career, the subject of nuclear disarmament has kept reappearing. Now both he and his agenda face the ultimate test: limiting nuclear arms at the very moment many experts fear the beginning of a second nuclear age and a rush of new weapons states - especially if Iran proves capable of making atomic warheads.
"I personally came of age," Mr. Obama wrote in "The Audacity of Hope," his second memoir, "during the Reagan presidency."
It was a time when President Ronald Reagan began a trillion-dollar arms buildup, called the Soviet Union "an evil empire" and ordered scores of atomic detonations under the Nevada desert. Some Reagan aides talked of fighting and winning a nuclear war.
The popular response was the nuclear freeze movement. Dozens of books warned that Mr. Reagan's policies threatened to end civilization and most life on Earth. In June 1982, a million protesters gathered in Central Park, their placards reading "Bread Not Bombs" and "Freeze or Burn." The nation's Roman Catholic bishops issued a pastoral letter denouncing nuclear war.
Many Columbia students campaigned for the freeze movement, which sought a halt to additional nuclear arms deployments. Mr. Obama explored going further.
In the interview, Mr. Obama noted that he was too young to "remember having to do drills under the desk." But as a student "interested broadly in foreign policy," he recalled, he focused on "a central question: how would the United States and the Soviet Union effectively manage these nuclear arsenals, and were there ways to dial down the dangers that humanity faced?"
In his senior year, he began Dr. Baron's seminar on presidential decision-making in American foreign policy. The first semester, starting in fall 1982, covered such cold-war flashpoints as the Cuban missile crisis - a dramatic study in the decision-making style of President John F. Kennedy. In the second semester, students focused on particular topics, and Mr. Obama wrote a lengthy paper about how to negotiate with the Soviets to cut nuclear arsenals.
"His focus was the nature of the strategic talks and what kind of negotiating positions might be put forward," Dr. Baron said. "It was not a polemical paper - not arguing that the U.S. should have this or that position. It was how to get from here to there and avoid misperception and conflict.
"He got an A," recalled Dr. Baron, who now runs a digital media business. Later, he wrote Mr. Obama a recommendation for Harvard Law School.
It was during that seminar that Mr. Obama wrote his Sundial article, profiling two campus groups, Arms Race Alternatives and Students Against Militarism. Photographs with the March 1983 article showed students at an antiwar rally in front of Butler Library.
Mr. Obama's journalistic voice was edgy with disdain for what he called "the relentless, often silent spread of militarism in the country" amid "the growing threat of war." The two groups, he wrote, "visualizing the possibilities of destruction and grasping the tendencies of distorted national priorities, are throwing their weight into shifting America off the dead-end track."
Despite Mr. Obama's sympathetic portrayal of the two groups, the article seemed to question the popular goal of freezing nuclear arsenals rather than reducing them, the topic of his seminar paper. Mr. Obama wondered if the freeze movement "stems from young people's penchant for the latest ‘happenings.' "
What clearly excited him was the Comprehensive Nuclear-Test-Ban Treaty, which would have ended the testing and development of new weapons, and thus, in the minds of arms controllers, the nuclear arms race.
The Reagan administration vehemently opposed the treaty. One Columbia activist, Mr. Obama wrote, argued that the United States should initiate the ban "as a powerful first step towards a nuclear free world."
That phrase - a "nuclear free world," which was Mr. Obama's paraphrase - would re-emerge decades later as the signature item of his nuclear agenda.
The article was lost for years - some of Mr. Obama's campaign advisers said they had heard of its existence and went looking for it, presumably to see if it contained anything that might prove embarrassing. It came to light on the Internet just before the inauguration, and some conservative bloggers called it naïve, anti-American and blind to the Soviet threat.
Precisely how the article found its way onto the Internet is unclear. But late last year, a Columbia alumni publication said it had learned of it from an alumnus, Stephen M. Brockmann, who also had an article in the same Sundial issue. Dr. Brockmann, now a professor of German at Carnegie Mellon University, said he found the issue "while rummaging through some old stuff." When he saw the Obama article, he recalled, "I could hardly believe my eyes."
After the Sundial article, Mr. Obama went silent on nuclear issues for the next two decades. In Chicago, where he worked as a community organizer, topics like remaking the schools, the welfare system and health care seemed a lot more urgent. The cold war ended. So did the protests.
But in 2003 Mr. Obama began his unlikely campaign for the United States Senate and answered a detailed questionnaire from the Council for a Livable World, an advocacy organization in Washington that evaluates candidates on arms control issues.
"He opposes building a new generation of nuclear weapons," the organization said in a fund-raising letter supporting Mr. Obama's candidacy. At the time, the Bush administration had proposed developing nuclear arms that could shatter deeply buried enemy bunkers.
"The United States has far more nuclear weapons than it needs," the organization quoted Mr. Obama as saying, "and any attempt by the U.S. government to develop or produce new nuclear weapons only undermines U.S. nonproliferation efforts around the world."
The organization said Mr. Obama also supported an American-financed effort to secure Russian nuclear arms, as well as ratification of the Comprehensive Nuclear-Test-Ban Treaty, still in limbo two decades after Mr. Obama wrote about it.
When he became a senator in January 2005, Mr. Obama zeroed in on arms control, an issue with little traction in the Republican-controlled Senate. Mark Lippert, now chief of staff of the National Security Council, recalled the senator's seeking his nuclear views when he applied for a Senate staff job.
Mr. Obama found a mentor in Senator Richard G. Lugar, Republican of Indiana, then chairman of the Senate Foreign Relations Committee and a longtime star of nuclear nonproliferation efforts. Later that year, Mr. Obama asked to accompany his Republican colleague on a trip to monitor Russian efforts to scrap nuclear arms and secure atomic materials from theft or diversion.
"When we got there, he was clearly all business - a very careful listener and note taker and a serious student," Mr. Lugar recalled.
During the presidential campaign, Mr. Obama seized a new opportunity, and political cover, by aligning himself with four of the biggest names in national security. They had decided to campaign for the elimination of the nuclear arsenals they had built up and managed as cold warriors.
There were two Republicans, Henry A. Kissinger and George P. Shultz, secretary of state under Mr. Reagan, and two Democrats, William J. Perry, secretary of defense under President Bill Clinton, and former Senator Sam Nunn, who has made fighting proliferation his life's work.
In a 2007 opinion article in The Wall Street Journal, the four men argued that the time was right to seek "A World Free of Nuclear Weapons," as the headline put it. President George W. Bush never invited them to the White House to make their case.
But Mr. Obama embraced the four wholeheartedly, echoing their message in campaign speeches in places like Chicago and Denver and in Berlin, where he spoke in July 2008 as the presumptive Democratic nominee.
"This is the moment," he told cheering Berliners, to seek "the peace of a world without nuclear weapons."
The nuclear world Mr. Obama studied and wrote about at Columbia bears little resemblance to the one he faces today.
Russia in many ways is the least of his challenges. Both Washington and Moscow want to renew the Strategic Arms Reduction Treaty, which expires late this year, and both say they want to shrink their arsenals.
More complex are problems posed by the rise of new nuclear states, chiefly North Korea, which has now conducted two nuclear tests, and Iran, which experts say will be able to build a warhead soon, if it cannot already. Pakistan has the fastest-growing arsenal, India's is improving, and Israel's nuclear capacity has never been publicly discussed, much less dealt with, by the United States.
The threat, Mr. Obama added in the interview, has "only been heightened with the emergence of extremist organizations such as Al Qaeda."
Mr. Obama and his aides say they want to address all these issues - though they have only recently begun to discuss strategy.
"We tried the unilateral way, in the Bush years, and it didn't work," a senior administration official said recently. "What we are trying is a fundamental change, a different view that says our security can be enhanced by arms control. There was a view for the past few years that treaties only constrained the good actors and not the bad actors."
Beyond the first step - deep cuts in American and Russian arsenals - is an agenda that has already provoked stirrings of discontent at home and abroad.
In January, in the journal Foreign Affairs, Defense Secretary Robert M. Gates, the lone holdover from the Bush cabinet, called for financing a new generation of longer-lasting and more dependable nuclear arms.
He was immediately overruled. Mr. Obama's first budget declared that "development work on the Reliable Replacement Warhead will cease."
Another focus of activity early this year was the Comprehensive Nuclear-Test-Ban Treaty. Its ratification faces a tough Senate fight. But his aides are already building a case that advanced technologies obviate the need to detonate weapons as tests of the American arsenal and can verify that other countries also refrain.
Critics argue that the North Koreas of the world will simply defy the ban - and that the international community will fail to punish offenders.
"If the implications were not so serious, the discrepancy between Mr. Obama's plans and real-world conditions would be hilarious," said Frank J. Gaffney Jr., a Reagan-era Pentagon official who directs the Center for Security Policy, a private group in Washington. "There is only one country on earth that Team Obama can absolutely, positively denuclearize: Ours."
Even more ambitious, Mr. Obama wants a Fissile Material Cutoff Treaty, which would bar all nations that sign it from making fuel for their atom bombs. But when asked how Mr. Obama would sell the idea to America's allies - primarily Pakistan, India and Israel - administration officials grow silent.
All this is supposed to culminate, next year, in an American effort to rewrite crucial provisions of the 1968 Nuclear Nonproliferation Treaty. Mr. Obama wants to strengthen inspection provisions and close the loophole that makes it easy for countries to drop out, as North Korea did in 2003.
Each of those steps would require building a global consensus. It would also mean persuading countries to give up the coveted freedom to make fuel for reactors - and instead, probably, buy it from an international fuel bank.
Most of all, Mr. Obama and like-minded leaders will have to establish a new global order that will truly restrain rogue states and terrorist groups from moving ahead with nuclear projects.
"I don't think I was that unique at that time," the president said of his Columbia days, "and I don't think I'm that unique today in thinking that if we could put the genie back in the bottle, in some sense, that there would be less danger - not just to the United States but to people around the world."