The Obama administration's decision to preview its National Security Strategy at West Point highlighted its coverage of security crises from Afghanistan to North Korea. But back-to-back events at Brookings with Hillary Clinton and Samantha Power today showed that the core of the strategy is a deeper argument about the central challenge confronting America -- the increased impact on our economy and security of a new global reality.

For two decades, the United States could take economic and security supremacy for granted. Three things have changed.

First, the global economic boom. Yes, boom -- remember? Before the crash, there were two decades of uninterrupted growth in the global economy, global trade, and global financial activity. The U.S. profited, but so too did China, India and Brazil, which grew into major economic players; so did several others, like Mexico, Indonesia and Turkey, which have emerged as the new middle powers.

Second, the Iraq war. Love or loath U.S. policy in Iraq, it launched us into sustained expenditure of financial and military resources alongside another draining war in Afghanistan. In the minds of the Vulcans, decisive U.S. victory in Iraq was to assert global order by force of -- well, force. The strategy backfired, and rising states from Ankara to Brasilia found few, if any, costs to opposing U.S. strategy in the Middle East -- and domestic political points to be won. The Obama administration is feeling the consequences in its Iran policy.

Third, the global financial crisis. The bust, when it came, reaffirmed the centrality of the U.S. in the short term. But it also showcased the growing weight of the emerging economies, which now lead the global recovery. Before Lehman Brothers collapsed, other big players may have disliked our Middle East policy, but they banked -- figuratively and literally -- on our stewardship of the global financial system. Since then, doubts have crept in, and a new assertiveness to match.

The net result is rising global influence and solidifying regional power for China, India, and Brazil -- and less room for maneuver for the US.

The administration will be criticized in predictable terms from predictable quarters for acknowledging any of this, even in tacit terms: for 'giving ground' to the emerging powers, for 'ceding' American supremacy, for forgetting to carry a big stick while talking softly. But that dog won't hunt. The Bush administration had begun to adapt to these changed realities towards the end of its tenure, and the Obama administration deserves credit for putting the new global realities front and center in its assessment of U.S. national strategy. The core concepts of revitalizing international order, pressing others to take up their responsibilities and working within, not against, multilateral arrangements are the right ones.

The tougher question is, will it work? Skeptics will point to Chinese heel-dragging and Brazilian gallivanting on Iran to say no. Optimists will point to Chinese cooperation on the financial crisis, and everybody's cooperation on Somali piracy and counter-terrorism, to say yes.

The reality is, we don't know. There's a struggle in Beijing between betting on cooperation with the US, and those who seek sharper competition. A pro-U.S. strategy in India has the high ground for now, but divisions remain. The better angels in Brazil's foreign ministry can't quite hold back Lula's dalliance with global populism -- an October election there may tilt the balance.

But we know this much: if the U.S. doesn't try, no one will succeed. None of the emerging powers can underwrite stability, and none that are serious want the job. The emerging powers may not play ball, and if so, we'll be in a lose-lose global game. But only U.S. strategy can pull us into win-win, and the Administration is right to try. Making this point to the American people won't be popular; but reality is reality, and denial does not a strategy make.

Article Highlights: 

• A recent model reveals that sheltering could save tens of thousands of lives after a nuclear terrorist attack in a large city such as Washington, D.C.

• However, as a society, we have largely forgotten about the importance of sheltering--a mainstay of Cold War-era civil defense training.

• That's why it's incumbent upon the federal government to immediately start a comprehensive public education campaign about the benefits of sheltering during a nuclear terrorist attack.

Of the 15 terrorism and natural disaster scenarios used by the Department of Homeland Security for planning purposes, the first scenario is the most feared: Terrorists detonate a 10-kiloton improvised nuclear device at ground level in the National Mall in Washington at 10 a.m. on a weekday morning.

In an attempt to understand what can be done to mitigate the consequences of such an attack, I, along with Stanford graduate students Sylvie Denuit and Youngsoo Choi, constructed a detailed mathematical model of this scenario that includes the initial effects of the detonation, the radiation fallout in subsequent days, the traffic flow of vehicles exiting the city, and the behavioral responses with respect to shelter versus evacuation. (Our full study will appear in an upcoming issue of the journal Risk Analysis.)

The results are on the order of what happened in Hiroshima nearly 65 years ago: Approximately 80,000 people would die from the immediate effects of the blast and heat and the radiation generated in the first minute. (These numbers are rough estimates and depend upon a number of irreducible factors, including the precise weather conditions.) Additionally, fallout--radioactive material carried by the explosive force and prevailing winds for up to 20 miles--would kill 20,000-40,000 pedestrians (i.e., commuters and residents without access to a vehicle) and 20,000-60,000 people in vehicles. The lower range represents the case in which most people shelter in basements or large buildings (office or residential) for 12-24 hours after the blast; the upper range represents the case in which most people attempt to immediately evacuate (by foot or vehicle).

These 60,000 saved lives far exceed the number of lives that would be saved in our model by medical care. Transfusion support and antibiotics obviously have the potential to save many lives, but such care will be practically impossible in the aftermath of a nuclear terror attack.

More to the point, as a society, we have forgotten about the importance of sheltering--a mainstay of Cold War-era civil defense training. This is partly because there isn't a scientific consensus on the shelter versus evacuation decision. Recommendations range from "evacuate if you can do it quickly" to "everyone shelter-in-place." Subtler strategies include "shelter unless you're in an area that will receive a potentially lethal dose of radiation" and "evacuate if your shelter isn't very good and you can rapidly get away from the plume."

Our analysis suggests that there is only a tiny fraction of people who would be better off by evacuating. And we should note that these people won't know who they are when the decision about evacuation needs to be made. Accurate plume information--the cloud can be irregularly shaped due to different wind directions at different altitudes--and travel-time estimates won't be available, and the ability for the government to communicate to those impacted by the attack will be extremely limited, perhaps restricted to battery-powered radios.

And even if the information and communication were perfect, historical data suggests that citizen compliance to a government-managed evacuation would be far from perfect. Although just 3,500 people within a 5-mile radius of Three Mile Island were told to evacuate when the plant melted down in 1979, 200,000 people within a 25-mile radius actually evacuated. Further, a 2007 survey found that the self-evacuation after a dirty bomb attack would be 65 percent in the absence of government advice and 39 percent if the government advised against evacuation. Moreover, our traffic-flow calculations suggest that even if a small percentage of those who aren't supposed to evacuate do so anyway, all of the evacuees will be stuck in traffic jams and therefore, exposed to much more radiation, especially because vehicles provide almost no protection from fallout.

Thus, the only robust strategy is to advise everyone to shelter.

To start implementing such a planned response, the government must first relinquish control of consequence management to our citizenry and then initiate an aggressive public-education campaign. The irony is that U.S. government websites currently contain excellent advice--including "everyone should shelter"--but they have neglected to tell people about them. Consequently, Homeland Security needs to get its message out creatively (how about Kiefer Sutherland, a.k.a. Jack Bauer, as the department's primary spokesman?); simply ("stay indoors for 12-24 hours"); and broadly (ask companies near large cities to have simple sheltering strategies).

The cost for such an educational campaign would surely be less than what we spend on other catastrophic terror threats ($877 million contract for an anthrax vaccine). The bottom line: The public must be educated about this issue now, because it's a lesson we don't want to learn from experience.

Leaders or representatives from 47 countries recently attended the nuclear security summit in Washington. By holding a bilateral meeting with U.S. President Barack Obama and delivering an important speech at the summit, Hu Jintao highlighted China's positive image for people across the globe and helped reverse the deterioration of US-China relations.

Obviously, it takes a long path toward establishing a global mechanism to counter nuclear proliferation and nuclear terrorism. Many of these leaders were not quite sure whether they would come away from the summit empty-handed.

However, they decided to attend the summit mainly to respond positively to Obama, who had launched a number of initiatives to build a nuclear-free world. The same is true for Hu Jintao and his decision to attend the summit.

Hu's visit to Washington will help lead the bilateral relations toward a positive direction. Although some disputes continue between the two countries, Hu's visit to Washington will no doubt contribute to lowering U.S. hostility toward China.

Earlier, the rapid increase in GDP had stimulated some Chinese diplomats to take blind pride in dealing with their foreign counterparts. Now, it is time to rethink whether it is necessary to adhere to the well-established principle of keeping a low profile in handling Sino-American relations.

China's GDP will soon become the second largest in the world. Who is the greatest beneficiary from the pursuance of this principle over the past three decades? Needless to say, it is China.

Now, China is just halfway through its course of "peaceful rise." In the foreseeable future, the United States will remain the No. 1 power in the world. Two decades from now, who will become the greatest beneficiary if China, as the biggest developing country, is able to maintain stable relations with Washington? Obviously, the answer is China.

In his opening statement at the summit, Obama pointed out that in today's world, the world has reduced the risk of a nuclear war between big powers, but the threat of nuclear terrorist assaults is increasing. He is right. Terrorists can penetrate all places throughout the world without leaving a trace.

It is difficult for all major powers, especially the United States, to detect and prevent them from launching assaults including sudden attacks with "dirty bombs" as weapons. As such, the whole world faces the most serious security challenge.

Such a strategic assessment prompted Obama to convene the nuclear security summit as well as his earlier initiative of "a world free of nuclear weapons." Preoccupied by this assessment, he has spared no effort to promote the campaign of countering nuclear proliferation and nuclear terrorism.

To fight nuclear terrorism, the summit focused on establishing an international nuclear security mechanism. The United States and many countries face the threat of nuclear terrorism. China is no exception.

In case the East Turkistan separatists consider the timing is mature to intensify conflicts with Beijing, they will no doubt take whatever means necessary to penetrate nuclear facilities or acquire "dirty bombs." Moreover, the large-scale construction of nuclear power plants in China introduces more security challenges. China will be in the peak period of building such plants in the next two decades.

The ongoing construction of such plants scattered in coastal areas would expose the nation to threat. A terrorist attack on even one plant would result in consequences more serious than that of detonating a nuclear bomb over a city. Taking this into account, Beijing has adopted various measures to strengthen nuclear security in recent years.

As a positive response from China to the international community, Hu Jintao made the decision to attend the summit, which reflects that Beijing and Washington actually are sharing common interests by making joint efforts to establish a global mechanism for countering nuclear proliferation and nuclear terrorism.

This action indicates that Beijing regards nuclear terrorist assaults as a huge threat to national security interests and it hopes to strengthen international cooperation to limit or even eliminate this type of threat.

Also, this decision has indeed enabled China to avert a head-on collision with the United States and helped reverse a deterioration of U.S.-China relations. Based on this, we can suppose that Beijing is able to conduct strategic adjustment at a critical moment and formulate appropriate foreign policies.

The release last week of the Obama administration's Nuclear Posture Review brings long overdue attention to the vital issue of U.S. strategic posture. Issues raised in the NPR and START have reinvigorated a crucial national nuclear dialogue that has been missing.

As the chairman and vice chairman of Congress's bipartisan Strategic Posture Commission, which issued its report last May, we have watched with great interest the administration's steady progress this past year on its Nuclear Posture Review and the START negotiations.

Themes from our report run through the Nuclear Posture Review and are embodied in the new START agreement. While debate and disagreement must be part of the crossfire in this renewed nuclear dialogue, we want to emphasize important dimensions of both the Posture Review and START treaty that figure prominently in our bipartisan report.

Now that the NPR is completed, we see that it is compatible with our recommendations. The review gives a comprehensive and pragmatic plan for reducing nuclear risks to the United States. We believe it offers a bipartisan path forward - while allowing for healthy disagreements on specific issues.

And it incorporates many of our points - such as pursuing a quick and modest reduction of nuclear weapons with Russia and sustaining the nuclear triad of land-based ICBMs, sea-based SLBMs and bombers. It also recognizes that nuclear weapons safeguarded U.S. security during the Cold War by deterring attack and that we will need them for deterrence in the foreseeable future, as long as others also possess them.

We also see that the NPR puts special emphasis, as our report recommended, on improving the nation's complex nuclear infrastructure and enhancing programs to recruit and keep the nation's best scientific minds. The administration's commitment to increase investment in our national laboratories also ensures that they continue their important role in sustaining a safe, secure and effective nuclear arsenal and in solving many other problems facing the nation.

The review is correct to make preventing nuclear terrorism and proliferation the top priority, while also seeking to strengthen deterrence and to reassure U.S. allies and recognizing the importance of strategic stability with Russia and an emerging China. Our commission reached the same conclusions.

The NPR's changes in U.S. declaratory policy - especially the assurance that Washington "will not use or threaten to use nuclear weapons against non-nuclear parties to the Nonproliferation Treaty that are in compliance with their nuclear nonproliferation obligations" - go beyond our recommendation that the U.S. retain "calculated ambiguity."

It is, however, a sensible variation on a theme that the U.S. should support nonproliferation while preserving deterrence for itself and its allies.

We also note that the NPR chose, as we advised, to avoid adopting a "no first use" policy for nuclear weapons while narrowing the scope of possible first use to "extreme circumstances" - language that was in our bipartisan report.

We believe that the substantial edge the U.S. has developed in conventional military capabilities, which the NPR notes, permits this country to sharply reduce reliance on nuclear weapons. But we caution those who make light of this major U.S. strategic advantage and its implications.

We support the NPR's call for the U.S. not to develop new nuclear weapons now. Our report similarly called for a case-by-case approach to extending the life of today's warheads. And we agree that the focus should be on safety, security and reliability - not developing new military capabilities.

The NPR echoes our call to negotiate a worldwide end to the production of new fissile materials - the key ingredients of nuclear weapons.

Our final report strongly endorsed the U.S. deterrence policy to cover our allies and partners with the U.S. nuclear umbrella - an objective the NPR also embraces.

The report suggested deploying proven missile defenses against threats such as North Korea and Iran but emphasized, as the NPR does, that these defenses should not be so big as to encourage Russia to add warheads to counter them, which would only undermine efforts to reduce nuclear weapons. We included China as well as Russia in this.

But in two areas, we believe the NPR might have fallen short of the mark.

First, we understand that the review considered declassifying additional information about the size and composition of the U.S. nuclear stockpile. It should have done so. This would demonstrate U.S. leadership on the transparency that is needed to secure nuclear materials globally and to bolster strategic stability with Russia and China.

Second, the NPR called for the consideration of conventional "prompt global strike" capabilities. But it did not explain whether these systems would have a niche role against small regional powers such as North Korea or be an ultimate substitute for nuclear weapons in deterrence with Russia and China.

We feel the former is the only sensible approach. Keeping this issue ill-defined creates needless anxiety in Moscow and Beijing that could lead to future problems.

Even with these two caveats, the 2010 Nuclear Posture Review makes important strides in charting a sustainable bipartisan path forward for the United States.

Healthy disagreement over some NPR specifics should not obscure the valuable contribution it makes to advancing U.S. security interests - resting, as it does in part, on our bipartisan 2009 Strategic Posture Commission report.

William J. Perry served as secretary of defense in the Clinton administration. He was chairman of the Congressional Commission on the Strategic Posture of the United States. James R. Schlesinger was the nation's first energy secretary and served as secretary of defense from July 1973 to November 1975. He was vice chairman of the Congressional Commission on the Strategic Posture of the United States.