OVER the last three years, as I delved into the world of American nuclear weapons, I felt increasingly as though I had stepped into a time warp. Despite the nearly total rearrangement of the international security landscape since the demise of the Soviet Union in 1991, the rise of Islamic terrorism and the spread of nuclear materials and technology to volatile nations like Pakistan, North Korea and Iran, the Defense Department remains enthralled by cold war nuclear strategies and practices.

Barack Obama took office determined to change that. He has made progress on many fronts. Last week, he outlined a new, no-frills defense strategy, downsizing conventional forces. He now needs to double down on his commitment to refashion nuclear forces. He should trim the American nuclear arsenal by two-thirds to bring it down to a sensible size, order the Pentagon to scale back nuclear war-fighting plans so they are relevant to contemporary threats, remove most American intercontinental, land-based missiles from high alert and drop the quaint notion that a fleet of aging B-52 bombers can effectively deliver nuclear weapons to distant targets.

This agenda is not only desirable, it is doable without undercutting American security. It would save tens of billions of dollars a year, a relatively small amount by Pentagon standards, but every billion counts as Leon E. Panetta, the defense secretary, trims his budget. And the steps can safely be taken without requiring reciprocal moves by Russia that must be codified in a treaty.

For the last few months, the Obama administration has been conducting a classified review of the doctrines and operations that determine the shape and potential uses of America’s nuclear armaments. If the president pushes back against the defenders of the old order at the Pentagon and other redoubts of the nuclear priesthood, he can preserve American security while making the United States a more credible leader on one of today’s most critical issues — containing the spread of nuclear weapons. Like a chain smoker asking others to give up cigarettes, the United States, with its bloated arsenal, sounds hypocritical when it puts pressure on other nations to cut weapons and stop producing bomb-grade highly enriched uranium, the key ingredient of a crude nuclear weapon.

American actions alone won’t end the proliferation danger, but American leadership is essential to any hope of containing the threat.

Sam Nunn, the former chairman of the Senate Armed Services Committee, and anything but a dove over the years, rightly warns that the spread of weapons and the means to make them may soon reach a combustible stage where New York, Washington, Moscow, Tokyo or London is at risk of a nuclear terrorist attack.

Mr. Nunn and other keepers of America’s cold-war armory, George P. Shultz and Henry A. Kissinger, former Republican secretaries of state, and William J. Perry, a former Democratic defense secretary, have banded together in recent years to press, among other things, for cutting nuclear forces, de-alerting missiles and, ultimately, eliminating nuclear arms. Mr. Obama has embraced their aims and welcomed them to the Oval Office. Their high-powered, bipartisan alliance, if adroitly employed by the White House, ought to provide some political cover as Mr. Obama reshapes nuclear policy while running for a second term.

There is no national security rationale for maintaining an arsenal of some 5,000 warheads, with nearly 2,000 arms ready to use on short notice and the rest in reserve. We don’t need thousands of warheads, or even hundreds, to counter threats from countries like Iran or North Korea.

The only conceivable use of so many weapons would be a full-scale nuclear war with Russia, which has more warheads than the United States. But two decades after the collapse of the Soviet Union, even Vladimir V. Putin, with his authoritarian bent, is not about to put Russia on a collision course with the United States that leads to nuclear war. China, equally unlikely to escalate tensions to the nuclear brink, probably has fewer than 400 warheads and a policy to use them only in self-defense. Pakistan has roughly 100, North Korea fewer than 10 and Iran, so far, zero.

The United States could live quite securely with fewer than 1,500 warheads, half in reserve. Defenders of the nuclear faith claim we need 5,000 weapons as a hedge against warheads that may become defective over time. But an elaborate Energy Department program to maintain and refurbish warheads, the Stockpile Stewardship Program, has proved highly effective.

Another oft-cited reason for increasing our arsenal is that the Pentagon’s nuclear war-fighting plans still call for striking hundreds of targets in Russia and China, as well as dozens of sites in a number of other publicly unidentified nations — presumably Iran, North Korea and Syria — considered potentially hostile to the United States and eager to possess unconventional weapons.

Washington’s current nuclear war plans remain far too outsize to deal with any plausible attack on America. Mr. Obama could remove some nations from the hit list, starting with China, and tell his generals to limit the number of targets in the countries that remain.

The oversize American nuclear arsenal features an equally outdated reliance on long-distance bombers. The days when lumbering B-52 bombers could play a central role in delivering nuclear weapons — memorably spoofed in Stanley Kubrick’s “Dr. Strangelove” — ended decades ago. Mr. Obama should ground the bombers and depend on land- and sea-based missiles.

The high-alert status of America’s intercontinental ballistic missiles is another anachronism. There are few circumstances that might require the United States to quickly launch nuclear-tipped missiles, and missiles on high alert are an invitation to an accident, or impulsive action. In the first year of his presidency, Mr. Obama outlined an ambitious nuclear weapons agenda. Absent new action, Washington will remain frozen in a costly cold war posture.

Philip Taubman is a former New York Times bureau chief in Moscow and Washington and the author of “The Partnership: Five Cold Warriors and Their Quest to Ban the Bomb.”

Abstract

As the diplomatic standoff in North Korea enters its fourth year, the crisis atmosphere on the Korean peninsula sparked by Pyongyang's military actions in 2010 has eased. Pyongyang has agreed to return to the diplomatic table, its hand strengthened by advancing its nuclear program in the interim. Washington and Seoul remain reluctant to engage, having been burned by Pyongyang's clandestine uranium enrichment program unveiled in 2010. The authors argue that re-engagement, with the immediate objective to stop a third nuclear test and prevent further missile tests, is imperative to contain the nuclear threat for now; preventing the nuclear program's expansion and preparing the way for the ultimate denuclearization of the peninsula—critical goals—must be left to a second step.

Note: There is a supplement to this piece with detailed overhead imagery, additional analysis of Pyongyang's march toward a more threatening nuclear weapons capability, and brief commentary on how the accession of Kim Jong-un to leadership may influence North Korea's nuclear trajectory. Click here to access "North Korea from 30,000 Feet"

An excerpt from "Implementing Change: Organizational Challenges" (pp. 309-310):

Improving organizational performance is never easy. As sociologist Jim March has noted, success requires that organizations balance exploration the search for new ways of doing things with exploitation, the ability to harness new practices and jettison older, less effective ones (March, 1991). These challenges confront all organizations, but two factors make them more acute for intelligence agencies. The first is bounded rationality (Simon, 1976). In the theoretical world, individuals have the luxury of perfect rationality, seeing all of the relevant options, assessing trade-offs with clarity, and making the best decisions. The real world is not as nice. There, rationality is inherently limited or bounded by uncertainty, imperfect information, and cognitive constraints that lead individuals to make decisions that appear to be “good enough”—but may turn out to be nowhere close (Simon, 1976). Intelligence officials have the toughest time of all, confronting bounded rationality problems in spades. Their job is to give policy-making customers decision advantage amidst swirling uncertainty, missing information, enemy deception and denial, and fast-changing events that are often unforeseeable, even to the participants themselves.

The second acute intelligence challenge is secrecy. As I discuss below, the more specialized any organization becomes, the harder it is for any one part of the organization to understand or improve what another part is doing, a phenomenon that sociologists call “structural secrecy” (Vaughan, 1996). In the classified universe, of course, this structural secrecy is compounded by actual secrecy, which protects vital information from adversaries, but also compartmentalizes information, ideas, organizations, and practices to a much greater extent.

Despite the intelligence community’s (IC’s) unique challenges, the fields of organization theory and political science offer useful insights and cautionary warnings about the organizational side of improving intelligence analysis. The chapters in Part II (Analytic Methods) of this volume mine an array of relevant literature for the best analytic tools to improve intelligence analysis. Here, we turn to a different task: Examining a broad sweep of relevant social science research with an eye to identifying which organizational factors impede or facilitate effective analysis. Worth underscoring, though, is the fact that social science does not offer ready-made instructions about how to make intelligence analytic improvements stick. However, it does offer some useful generalizations that can illuminate the trade-offs and challenges involved to guide more effective implementation.

Contention and Trust in Cities and States explores cities and nation-states throughout history and around the world, bringing together the research of top scholars. It takes as a jumping-off point the work of the late Charles Tilly, but proceeds varied topics ranging from how today’s drug cartels undermine nation-states to how cities, nation-states, and empires treated religious minorities in the middle of the last millennium. Threaded throughout are themes of city-state relations, trust networks and commitment, democracy and inequality, and the importance of historical legacies in shaping state structures, practices, and capacities.