Since developing nuclear weapons in 1945, the United States has maintained the right to use them first against another country, whether or not that country launched a nuclear attack at the United States. Over the past several months President Obama considered changing that “first-use” optional policy to one under which the US declares that it will only use nuclear weapons in response to a nuclear attack. China and India have such policies today. Russia had this policy, but in 1993 changed it to reserve the right to use nuclear weapons in response to attacks that threaten the survival of the Russian state, even if those attacks do not employ nuclear weapons.

Press reports now assert that key members of the president’s cabinet, including Defense Secretary Ashton Carter, Secretary of State John Kerry, and Secretary of Energy Ernest Moniz all opposed the adoption of a US nuclear no-first-use pledge, and the president ultimately accepted their advice. There are reasonable arguments, reviewed below, on both sides of the no-first-use debate. Unfortunately, there may be negative consequences for raising the issue publicly and then rejecting it. Such consequences could include a hardening of reliance on nuclear weapons by Russia, China, and North Korea, intensification of the global nuclear arms race, further weakening of the Non-Proliferation Treaty and a possible reversal by China of its own no-first-use pledge in the near future.

These consequences are likely because the “power ministries” of the United States—those that wield diplomatic and military power to implement national security strategy—have just re-asserted their belief in the power and value of nuclear weapons for the indefinite future. Combined with plans to modernize the entire US nuclear arsenal over the next 30 years, this pro-nuclear message contradicts President Obama’s 2009 Prague speech and its focus on the dubious value of nuclear weapons. In the speech, Obama said, “Just as we stood for freedom in the 20th century, we must stand together for the right of people everywhere to live free from fear in the 21st century. And as a nuclear power—as the only nuclear power to have used a nuclear weapon, the United States has a moral responsibility to act. We cannot succeed in this endeavor alone, but we can lead it, we can start it… So today, I state clearly and with conviction America's commitment to seek the peace and security of a world without nuclear weapons.”

The choice to reject a no-first-use pledge is a choice of fear over hope. Carter, Kerry and Moniz, like the three wise monkeys, see no evil in claiming the right of the United States to defend itself and its allies by threatening to kill millions of innocent people from hundreds of different nations throughout the world—the outcome of an exchange of nuclear weapons using only a small fraction of the existing US arsenal. In essence, they told the president that he should not risk devaluing the investment in fear that the potential first use of US nuclear weapons represents. These cabinet officers embrace the postulated ability of nuclear weapons to scare adversaries into inaction. In other words they told the president he was wrong in Prague, and the nuclear fear that he pledged to reduce is actually good for America, because it is a handy tool that underwrites the world order, discourages enemies from doing things we would rather they not do, and calms our allies. The three wise men told the president that he must continue to place national security above human security, that it is OK to value American lives and the lives of its military allies above all other human lives.

There is only one problem with this counsel: It is ultimately unjustifiable and unsustainable within the value system that America claims to embrace. Instead of saying, “Gentlemen, thank-you for your advice, but I am going to declare that the United States will not use nuclear weapons first,” President Obama apparently has abandoned his Prague Agenda. But a no-first-use policy should not be permanently taken off the table of US nuclear options. A future president may see its wisdom and be less constrained by immediate circumstances from embracing it as official policy. Perhaps President Obama will continue to advocate this change after leaving the presidency.

The United States could achieve several objectives by adopting a no-first-use policy. First, by asserting that the United States sees nuclear weapons as fundamentally different from all other weapons and reinforcing an international norm against their use, a no-first-use policy would strengthen the global taboo against use of nuclear weapons. This taboo has emerged in recognition of the horrific consequences of nuclear weapons use and in acknowledgement of the fact that no political or military objectives would justify the consequences of nuclear war.

A no-first-use pledge may also reduce the risk of Russian or Chinese nuclear miscalculation during a crisis by alleviating concerns about a devastating US nuclear first-strike. If they were launched first in a crisis, a moderate portion of US nuclear forces could sharply degrade the retaliatory capability of Russia or China. This fact motivates these states to consider using their nuclear weapons early in a crisis to avoid their potential destruction. If the United States declared a no-first-use policy and postured its nuclear forces accordingly, perhaps by reducing the alert status of its strategic ballistic missile force, China and Russia’s nuclear trigger fingers would be less itchy.

The 2010 US Nuclear Posture Review and the 2013 Nuclear Employment Guidance both state it is in the US national interest to reduce the role of nuclear weapons in national security strategy. Clearly, a decision not to use nuclear weapons unless attacked with nuclear weapons would help achieve the objective of reducing their strategic role; under current doctrine, the United States could use nuclear weapons in response to conventional, chemical or biological attacks.

Finally, the United States should make a no-first-use pledge to demonstrate US leadership in asserting that nuclear weapons must remain weapons of last resort. It is dangerous and ineffective to rely on nuclear weapons to deter non-nuclear threats. Such policies could transform even a minor provocation or incident into a nuclear crisis and increase the chances of unwanted escalation. A no-first-use pledge is a confidence-building measure; it advertises that as its official policy, the US will retaliate to provocation or aggression with graduated and proportional levels of military force, consistent with international laws on armed conflict. Potential adversaries will continue to know, despite a US no-first-use pledge, that if their attacks cause catastrophic damage or threaten the survival of the United States or its allies, the capability for a potential nuclear response remains.

The arguments of opponents to a no-first-use policy are unconvincing. They claim to know that such a policy shift would be interpreted in the minds of Chinese, Russian, or North Korean leaders as weakness and lack of resolve. They worry that these leaders would now believe that they could safely attack America or her allies, and, and as long as they didn’t use nuclear weapons, they would remain immune from nuclear retaliation.

This concern does not hold up under reasonable analysis. Let’s put the shoe on the other foot. China has a nuclear no-first-use policy. Let’s assume (unrealistically) that Russia has re-adopted one, too. Do we honestly believe that US defense planners would now conclude that such declarations significantly lower the risks accompanying a decision to destroy Chinese military facilities on their newly built islands in the South China Sea, or to invade Kaliningrad at the first sign of a new Russian thrust in Eastern Ukraine? Our planners know that such actions—even though they did not involve nuclear weapons use—carry immense risk, because they would taken against nations that have the capability to respond with nuclear weapons, no matter what their declaratory policy. Similarly a US no-first-use declaration will not prompt Russian, Chinese, or North Korean leaders to ignore the fact that non-nuclear warfare against the United States or its allies carries an inescapable risk of escalation, especially if vital American interests or those of its allies are attacked. (Fortunately, the United States and its allies have the military capabilities to deter and, if deterrence fails, to respond to non-nuclear attacks with powerful conventional forces and keep nuclear forces where they belong, in the background as weapons of last resort.)

A no-first-use pledge should be adopted because words and declared policies matter. Nuclear deterrence is an unavoidably risky business, and nuclear war would bring on unmatched human tragedy. Evidence is mounting that nuclear deterrence is a far riskier and more fragile enterprise than previously thought. A chain of events leading to nuclear war can emerge, even when no political leader believes it is in the interest of his country to initiate war, and both sides act in a manner intended to avoid it. It is therefore vital that the United States take all possible steps to eventually escape the rickety and unsustainable system of nuclear deterrence. US leaders should always be searching for ways to climb down the ladder of mutual nuclear threats, not up it.

It might be acceptable to leave US nuclear weapons policy unchanged if current policies kept America and its allies reliably safe. They do not. The human beings that operate nuclear weapons and the computers and communications technologies used for their employment are all prone to error. The documentary film, Command and Control, which begins major screenings this month, demonstrates this vividly.

A no-first-use pledge takes this reality into account. It is an official leaning away from the paradoxical logic of nuclear posturing, threats, and coercion that can cause unintended escalation during even a minor a crisis. The United States and its allies do not benefit from remaining ambiguous and declaring nuclear weapons to be options always “on the table,” however small the stakes of a dispute or how minor a provocation. Such policies stand only to increase the chances of a deadly mistake and encourage other states to move toward policies where any challenge to their interests might be answered with nuclear threats.

No one can know with certainty how US adoption of a no-first-use pledge will influence the dynamics of deterrence. It is likely not to cause much change. But it offers at least the possibility of attenuating tensions in a crisis and communicating to the world that the United States views nuclear weapons use as a last resort. Such statements are increasingly important, especially in light of the current tenor of US-Russian and US-Chinese relations. A no-first-use pledge also provides the United States with a stronger position from which to advocate for other nations to adopt similar policies and improves compliance with obligation under the Non-Proliferation Treaty's 2010 Action Plan, which calls on all member nations to reduce the role of nuclear weapons in their security strategies.

Critics deny that these are significant benefits to US and allied security. But if the benefits are to some degree intangible, they are also vital to the US goals of leading the world, step by step, away from security policies based on the threat of mutual annihilation. Current nuclear weapons policies are fraught with unacceptable levels of risk and cannot be sustained over the long term. A no-first-use pledge is a policy change that will ultimately strengthen the security interests of the United States and its allies by indicating that America acknowledges the nuclear status quo as unsustainable and is willing to adopt policies that reduce the role of nuclear weapons in current and future security strategy.