The 2026 United States’ war against Iran is a matter of international and domestic political controversy. Regardless of its outcome, the trajectory already suggests important lessons about the continuing relevance of nuclear weapons and nuclear deterrence for international peace and security.  

The end of the Cold War and the demise of the Soviet Union led to a shift in American and allied European expectations about relations with Russia and the importance of nuclear weapons. Many assumed it that a new world order had emerged that validated American triumphalism and the superiority of democracy and capitalism. The United States in the 1990s and early 2000s, despite the 9/11 attacks and the global war on terror, remained the preeminent international promoter of world order and international peace.  

Similar optimism about the twenty-first century led to the diminished appreciation for nuclear weapons and its effect on deterrence. Researchers who focused on nuclear deterrence became fugitives in an intellectual climate that favored the study of unconventional warfare, terrorism, human rights, and climate change. Only a small coterie of academics and think tank specialists continued to warn that the significance of nuclear weapons and its deterrent effect would not depreciate in the new world order, and, in fact, that they might prove to be even more relevant and challenging for world peace and international security than hitherto. With the advantage of hindsight, the optimism for a peaceful new world order and the expectations of diminishing nuclear relevance were clearly a mistake. New challenges to international security and political stability arose on several fronts.   

First, political relations between the United States, its North Atlantic Treaty Organization (NATO) allies, and Russia dramatically deteriorated because of Russia’s aggression against Ukraine. Putin’s war on Ukraine created an existential threat to European security, supported by Russia’s nuclear modernization and increasing diversity of advanced conventional weapons. The expiration of New START, the last remaining nuclear arms control treaty, did not help.  

Second, China emerged as a third and soon to be nuclear peer. They are moving steadily to rival the United States and Russia, all while expanding regional aspirations. This leaves the United States facing a future that, even with modernization of all three legs of the nuclear triad, will lag significantly behind the combined Russian and Chinese nuclear forces by 2035.  

Additionally, Russia also has thousands of non-strategic or tactical nuclear weapons and maintains a collection of delivery systems deployed and/or stored for deployment. In comparison, the United States currently deploys some 200 tactical nuclear weapons in five European countries for delivery by dual capable aircraft (DCA) under NATO. Russia also moved the needle on deployable long range hypersonic land based and air delivered nuclear weapons. Russian experience with drones in Ukraine challenge preexisting assumptions about deterrence and defense in Europe. The West should expect more change. The possibility of simultaneous Russian and Chinese attacks in the European and Indo-Pacific theaters with conventional weapons, supported by the threat of nuclear escalation, cannot be ruled out by American and allied military planners.  

Third, the successful containment of nuclear proliferation by the Non-Proliferation Treaty, and other restraints, is now at imminent risk. Iran’s nuclear program has doubtless been set back by Israeli and American attacks. However, in the absence of regime change, Iran seems determined to continue with plans for uranium enrichment toward nuclear weapons. Even if Iran’s nuclear ambitions are temporarily contained by outside pressure or diplomatic agreement, other regional powers are already considering their own options.  

Saudi Arabia reached an agreement with the United States to support a larger nuclear energy program for the kingdom. The Saudis want not only to diversify energy sources, but hedge against an Iranian breakthrough to nuclear weaponization. Development of a “Shia bomb” or even a robust development of fissile material on the threshold of weaponization could affect decisions in Saudi Arabia, Turkey, and Egypt.  

Some critics of American and Israeli insistence that Iran is not permitted to develop nuclear weapons contend that the same arguments were made against North Korea’s nuclear ambitions, but a rogue North Korea has decided to establish a nuclear weapon program anyway. And like Iran, it is tied to Russia and China as supportive powers. On the other hand, North Korea is almost completely dependent on China for its economic survival and security guarantees, and China has made it clear that it opposes any North Korean nuclear first use or first strike unless Pyongyang itself is invaded.  

China enjoys North Korean saber rattling as a distraction from China’s own aggression. Thus, an important distinction between Iran and North Korea is that the latter is subject to friendly regional restraint on its nuclear ambitions. On the other hand, regional restraint against Iran’s nuclear trajectory is the responsibility of Israel, who is distrusted and surrounded by Arab countries.  

Finally, observers of American foreign policy cannot help but notice the difference in outcomes between adversaries that develop nuclear weapons and those that do not. The United States invaded and occupied Iraq and Afghanistan and, with support, assisted regime change in Libya. On the other hand, North Korea receives a light touch.  

Although not an American adversary, Ukraine gave up nuclear weapons and has faced Russian aggression and interference for at least two decades. This is despite American, British, and Russian guarantees of Ukraine’s sovereignty. Some Ukrainians must surely wonder whether nuclear abstinence was cockeyed optimism.  

Lastly, India and Pakistan fought three wars before either had acquired a nuclear arsenal. Since then, despite periodic skirmishes, the number of major wars between the two Asian nuclear powers is zero.  

The preceding does not imply that nuclear deterrence is infallible, nor that it is easy to accomplish. The United States today recognizes the need for tailored deterrence, based upon capabilities for assured retaliation, flexible targeting, escalation control, and war termination.  Continuing updates of threat assessments should be accompanied by appropriate modernization of strategic and non-strategic nuclear forces, as well as competitive breakthroughs in missile defense, hypersonic weapons, artificial intelligence, and cognitive science. The nuclear deterrent is also shrink-wrapped around expected challenges in the space and cyber domains. The CRINK (China, Russia, Iran, and North Korea) coalition poses continuing challenges to world order, including those that require strong nuclear equities. 

History shows that the world order is strongly linked to strategies that include nuclear weapons, which if anything, are becoming more diverse in this century. Western powers must recognize this plan accordingly. In the end, the worst option is to do nothing. 

Stephen J. Cimbala is Distinguished Professor of Political Science at Penn State Brandywine and the author of numerous works on nuclear deterrence, arms control, and military strategy. He is a senior fellow at NIDS and a recent contributor to the Routledge Handbook of Soviet and Russian Military Studies edited by Dr. Alexander Hill (Routledge: 2025). The views of the author are his own.

Iran Shows Why Nuclear Deterrence Still Matters was originally published on Global Security Review.