For decades, the United States treated the prospect of an Iranian nuclear weapon as an intolerable threat. Yet when Washington and Tehran went to war twice in roughly a year, America’s own nuclear arsenal provided remarkably little leverage.
In June 2025, the United States joined Israel in attacking Iran’s nuclear facilities. Iran retaliated against Israeli territory and a U.S. air base in Qatar. The following year, a far larger U.S.-Israeli campaign killed Supreme Leader Ayatollah Ali Khamenei and much of Iran’s senior military leadership while striking the country’s nuclear, military, energy, and transportation infrastructure. Tehran responded by attacking Israel, U.S. bases across the Persian Gulf, and regional energy infrastructure.
In neither war did America’s overwhelming nuclear superiority prevent Iranian retaliation or compel Tehran to capitulate. The paradox is striking: the weapon the U.S. had long insisted Iran must never possess proved largely incapable of shaping Tehran’s calculations, or determining the course of a war of choice that has consumed Trump’s presidency.
Indeed, nothing in Iran’s observable behavior during the conflict suggests that the prospect of American or Israeli nuclear use materially shaped its wartime decisions. Aside from President Donald Trump’s occasional angry outbursts on social media, Washington issued no explicit nuclear threats, and there is no public evidence that Iranian leaders regarded nuclear escalation as a plausible wartime contingency.
It was only after hostilities ended that Brig. Gen. Mohammad Reza Naghdi, a senior Islamic Revolutionary Guard Corps (IRGC) commander, publicly warned that any U.S. use of nuclear weapons would be a “mistake.”
Tehran’s wartime choices — including the decision to close the Strait of Hormuz — were responses to conventional military and economic pressure, not to America’s nuclear arsenal. Iran fought what its leaders regarded as a war of survival against two nuclear-armed states without visibly adjusting its strategy to account for possible nuclear use. Instead, Tehran relied on pre-existing capabilities. As Alireza Salimi, a lawmaker and member of the Iranian parliament’s presiding board, put it , “Under the current circumstances, the Strait of Hormuz is more valuable to us than a nuclear bomb.”
The Iran war is the latest example of a pattern stretching from the Falklands War in 1982 to Russia’s invasion of Ukraine. When a nuclear-armed state’s survival is not at stake, its nuclear arsenal provides remarkably little leverage to compel an adversary’s submission. Three wars involving nuclear powers across more than four decades point to the same conclusion: nuclear weapons may constrain escalation, but they rarely determine political outcomes.
The Falklands War
In 1982, the United Kingdom — a nuclear weapon state — sent a naval task force 8,000 miles to retake the Falkland Islands from non-nuclear Argentina. Several Royal Navy vessels initially carried nuclear depth bombs as part of their standard armament, but the weapons were removed from the task force and eventually returned to Britain as political and operational concerns mounted. The war itself was fought entirely with warships, aircraft, and infantry.
Historical records further indicate that British officials never seriously contemplated the threat of nuclear use, while Argentine officials calculated that the U.K. would be restrained by its own nuclear policies. This was a war over control of disputed territory, British national prestige, and potentially Prime Minister Margaret Thatcher’s political survival. Yet Britain’s nuclear arsenal provided no discernible coercive advantage and did not shape the conduct or outcome of the war.
If possession of nuclear weapons reliably generated coercive leverage whenever a state’s political stakes were high, the Falklands should have been a favorable case for exploiting it. Instead, the conflict illustrates the opposite: when nuclear use would be grossly disproportionate —and the threat of such use therefore non-credible — even an advanced nuclear arsenal may have little bearing on an adversary’s behavior or on the conduct and outcome of a conventional war.
Ukraine: The exception that isn't
Ukraine presents the harder case. Unlike Iran or Argentina, nuclear-armed Russia has repeatedly brandished its arsenal as an instrument of coercion since its 2022 invasion. Within days of the attack, Russian President Vladimir Putin placed Russia’s deterrent forces on a “ special regime of combat duty .” Former President Dmitry Medvedev and other senior officials subsequently issued repeated threats to use “ all available means ”; the Kremlin expanded the circumstances under which its nuclear doctrine permits use; and Moscow conducted additional strategic-force exercises in May 2026 amid battlefield setbacks.
This campaign had some effects, including generating a fear of escalation that contributed to some hesitation in Western capitals over providing Ukraine with long-range missiles and loosening restrictions on their use. But those threats neither compelled Ukraine to surrender nor reversed Russia’s battlefield and strategic failures, or ultimately prevented NATO states from supplying advanced military capabilities.
U.S. intelligence assessments have further concluded that Moscow would be most likely to cross the nuclear threshold only if the Russian state or regime faced an existential threat. Russia’s nuclear threats therefore exerted psychological pressure and bought time at the margins, but they neither delivered victory nor transformed the basic character of a war still being fought with tanks, artillery, missiles, and drones.
Even Moscow, then, operated within limits that were never seriously tested. The pattern is not unique to Russia: nuclear threats are most credible only when the state issuing them believes its own survival is at stake. None of these conflicts — Britain's war to reclaim the Falkland Islands, America's war with Iran, or Russia's invasion of Ukraine — placed the survival of the nuclear-armed state in jeopardy. Iran’s response was especially revealing: Tehran dismissed Trump’s demand for “ unconditional surrender ” and escalated instead, demonstrating how little coercive leverage America’s nuclear superiority provided.
These cases of nuclear restraint reflect a structural cost that applies to any nuclear power weighing escalation against a weaker adversary. Using nuclear weapons against a non-nuclear or substantially weaker adversary would carry reputational costs far exceeding any plausible battlefield gain. Such an attack would likely invite international condemnation, alienate allies, and even potentially fracture the domestic and international coalitions sustaining the war.
Argentina, Iran, and Ukraine could therefore fight nuclear-armed powers without treating nuclear use as a credible response to every escalation. Nuclear weapons may cast a shadow over such conflicts, but when their use would be plainly disproportionate, threats to employ them carry little credibility and provide limited leverage.
Deterrence not compellence
These three cases do not show that nuclear weapons are irrelevant. They reveal a narrower limitation: nuclear weapons are better at deterring actions than compelling them.
Nuclear weapons can raise the risks of intervention and place a ceiling on escalation. But because using them to achieve limited objectives would be disproportionate, they offer little leverage over a determined adversary, especially if the adversary is fighting for its survival. While they may shape the boundaries of a war, they rarely decide its outcome.
To be sure, some Iranian leaders may draw the opposite lesson: that only an operational nuclear arsenal could have prevented attacks on the country’s leadership and critical infrastructure. But the war could also reinforce Tehran’s preference for remaining a nuclear-threshold state. Iran’s most effective leverage came from capabilities it could actually employ to disrupt shipping through the Strait of Hormuz. Remaining at the threshold would preserve nuclear latency while avoiding many of the diplomatic, economic, and military costs of openly building a weapon.
Tehran may therefore focus on making its conventional forces more survivable, expanding its missile and drone capabilities, and strengthening its capacity for maritime denial. The lesson for Iran may be that usable conventional power offers more practical wartime leverage than a nuclear weapon whose principal value would lie in never being used.
Turns out having nukes provided the US very little leverage
Aggregated summary from an independent source. Read the original at ResponsibleStatecraft.