In the years since the Cold War ended, Americans generally have not thought much about nuclear weapons, the debate over their modernization, the role they play in American foreign policy, or the principles that guide U.S. nuclear deterrence strategy and policy. But the summer of 2016 is a notable exception, largely as a result of the Obama Administration’s public discussion of the wisdom of adopting a “no-first-use” nuclear weapons policy. Although the Administration has reportedly decided against such a policy, there are those, including some in the President’s inner circle, who are still urging President Barack Obama to make such a change.

A no-first-use nuclear weapons policy means that a country vows not to use nuclear weapons unless it is first attacked with nuclear weapons. Such a declaration would be a departure from the current U.S. policy of “calculated ambiguity.” Since the dawn of the atomic age, the United States has refused to specify exactly which scenarios would lead to the use of its nuclear weapons. The ambiguity created by having an undefined “red line” contributed greatly to deterrence during the Cold War—including deterrence of large-scale attacks conducted with non-nuclear weapons—and continues to do so today. The effect of changing this policy would be to make the United States and its allies less secure while failing to provide tangible nonproliferation benefits.

The very term “no-first-use” is misleading. While a nuclear weapon has not been used in anger for over 70 years, nuclear weapons are used every single day to deter large-scale conventional and nuclear attacks. Former Air Force Chief of Staff General Larry Welch points out that “we have used the nuclear forces every second of every day for 50 years.” Moreover, during those 50 years, humankind has experienced the most peaceful period in its history as measured by the number of conflict-related casualties as a proportion of the world’s population. This is due in large part to the devastating risks that nuclear weapons pose to any society that is attacked with them. For the United States and the Soviet Union, a large-scale nuclear exchange meant the end of society as Americans and Russians had known it. That risk led American and Soviet leaders to exercise a level of caution and restraint that was not exercised by German, Japanese, and other world leaders in the years leading up to World War II.

If the United States were to adopt a no-first-use policy, the perceived threat of nuclear conflict admittedly would decline. While a decline in the perceived threat of nuclear weapons use may seem like a good thing, however, it is actually dangerous because it is that very perceived threat that gives leaders who may be contemplating the use of force the chance for second thoughts that can prevent great-power war. This is an important point. Opening the door to great-power conflict, even if ever so slightly, is obviously a step in the wrong direction.

Nor are great-power conflicts the only dangerous challenge that nuclear weapons deter. Biological, chemical, and even well-organized and targeted cyber-attacks can be as devastating as nuclear attacks. Some proponents may claim that the combination of a no-first-use policy and American conventional superiority plays to America’s strength, but recent history suggests that simply using our conventional forces rarely achieves our political objectives. It is also worth noting that the U.S. military is overstretched and on the verge of a readiness crisis. In the European theater, for example, North Atlantic Treaty Organization (NATO) forces are judged by many to be insufficient to counter  a Russian military advance into the Baltics. Most important, the point of deterrence is to prevent a war from happening, which is frequently preferable to becoming engaged in a war even if one wins at the end of the day.

In the context of the no-first-use policy, we must keep in mind that President Harry Truman made the decision to use nuclear weapons against Japan to prevent an estimated 500,000 or more American casualties in a planned invasion of Japan. We cannot know that future Presidents will not find the nation in a similar situation in which using nuclear weapons could end a war and save thousands or even millions of American lives. Such a decision ought never to be taken lightly, but considering how many times we have been wrong about the future, changing a policy that has served the United States and its allies so well since the end of the Cold War would be at best naïve and at worst dangerous, particularly since security trends for the United States point in a negative direction.

Finally, a no-first-use nuclear weapons policy could result in more, not less, proliferation. America’s allies depend on U.S. nuclear guarantees. They do not develop their own nuclear weapons because they rely on the United States to defend them, a necessity that is all too real for countries like South Korea, Japan, Poland, and the Baltic States. We must remember that North Korea has threatened “a sea of fire” upon South Korea. Russia has threatened to use nuclear weapons against NATO allies in order to force the United States to deescalate a conflict. In the context of today’s threats and to strengthen deterrence, the United States does not specify the exact location of its red lines that would trigger an American nuclear response.

South Korea and Japan are technologically advanced and could rapidly join the club of nuclear weapons states should they lose confidence in the credibility of American deterrence. Increasing these nations’ uncertainty about U.S. security commitments undermines American nonproliferation policy. A no-first-use policy only adds to the already existing view that an American President is not likely to trade San Francisco or New York for Seoul or Riga.

The benefits of a no-first-use policy are unlikely to materialize as advocates suggest. Rather, the United States is much more likely to see a number of negative consequences. The old adage “peace through strength” is certainly applicable to nuclear weapons policy. No-first-use is antithetical to such a view and only works to undermine the credibility of American deterrence.

Further Reading on E-International Relations

• What Does the Death of the INF Say About the US’ Friendships?
• United States Foreign Policy in the Middle East after the Cold War
• Does Denuclearization Mean Giving up North Korea’s ‘Treasured Sword’?
• The Erosion of the Nuclear Taboo
• Opinion – North Korea’s Nuclear Tests and Potential Human Rights Violations
• Assessing Neutrality: The United States’ Role in the Diaoyu Islands Dispute