On 6 June 2025, the Washington-based think tank Atlantic Council published an analytical piece by Mark J. Massa, its nuclear and security expert, on Ukraine’s apparently successful drone strikes against Russia’s nuclear bombers stationed at one of its air bases. The article reflects a growing line of thinking in the U.S. strategic community: that attacking the nuclear assets of an enemy state with conventional weapons should no longer be considered a breach of the so-called nuclear taboo. “Ukraine’s drone strikes were a blow to the widely held belief that non-nuclear military attacks on nuclear-relevant facilities or assets will lead automatically to uncontrollable nuclear escalation,” Massa wrote.
American experts once took great care to preserve the sanctity of this nuclear taboo—an idea painstakingly constructed by U.S. political, military, and strategic elites after the Second World War. They strove to impress upon the world that nuclear weapons were not ordinary weapons of war but rather tools of deterrence to prevent conflict. A critical tenet of this doctrine was the norm against attacking an adversary’s nuclear installations. It was under American influence, for instance, that Pakistan and India signed the Agreement on the Prohibition of Attack Against Nuclear Installations and Facilities in 1988.
Massa’s latest article, however, suggests a shift in this traditional thinking. He writes:
“As I have argued previously, too many analysts of nuclear affairs appear to overweight the risk that if a nuclear-armed country is facing attacks on nuclear-relevant locations or assets by conventional weapon systems or dual-capable ones (systems relevant to both nuclear and conventional missions), then that country will feel overwhelming pressure to escalate to the use of nuclear weapons, perhaps even before assessing the extent of the attacks. This logic looks convincing. But it is empirically unsupported.”
He adds, “Russia may yet respond to the Ukrainian attack. But Russian nuclear retaliation in Ukraine seems unlikely, even after Russia lowered its stated threshold for nuclear use in September 2024. Ukrainian drone strikes on multiple Russian bomber bases would seem to be exactly the sort of attack that would trigger Russia’s lower threshold for resorting to nuclear weapons. Yet no such use has materialised.”
During the recent 12-day Iran–Israel war, Israel attacked Iranian nuclear sites several times. In the final days of the war, the United States used bunker-buster bombs on at least three of Iran’s nuclear installations. Thankfully, the International Atomic Energy Agency reported no radiation leakage, and Iranian authorities claimed the attacks posed no danger to the population. While Israeli recklessness is nothing new, the American decision to join in—and risk a potential nuclear accident—raises serious questions. Why did the U.S. abandon the very nuclear taboo it helped craft? The risk of a nuclear disaster was real. What are the implications of such attacks for the international system, and for nuclear stability in regions like South Asia?
Washington acted swiftly to prevent escalation in South Asia after strikes near a nuclear command centre, yet felt emboldened to bomb Iran’s actual nuclear sites
Reports suggest that U.S. Secretary of State Marco Rubio launched a diplomatic initiative to de-escalate tensions between Pakistan and India after receiving confirmation that Indian forces had struck Nur Khan Air Base with BrahMos cruise missiles. Though Nur Khan is not a nuclear facility, it is located near Pakistan’s nuclear command structure, according to international media. This stark contrast in U.S. policy is concerning: Washington acted swiftly to prevent escalation in South Asia after strikes near a nuclear command centre, yet felt emboldened to bomb Iran’s actual nuclear sites. Such inconsistency in nuclear policy is dangerous.
What explains this contradiction? The most plausible answer is that Iran is not yet a nuclear weapons state, and could not therefore retaliate with a nuclear strike. In contrast, both Pakistan and India are declared nuclear powers. As President Biden (and now Rubio) repeatedly stressed, American diplomacy had prevented nuclear war in South Asia. In other words, the U.S. went all-out to uphold the nuclear taboo in South Asia, while simultaneously breaking it in the Middle East. Will strategic planners in other regions now learn from this example? Or is the message that only superpowers are allowed to carry out such strikes without consequence?
A brief look into regional history offers more context. Until the 1990s, it was routine for Pakistani and Indian military planners to prepare attack strategies against each other’s nuclear sites. These made headlines frequently in the 1980s and early 1990s. As the Cold War ended, New Delhi and Islamabad began recognising U.S. leadership in global nuclear diplomacy, culminating in the 1991 Agreement on Non-Attack on Nuclear Facilities. But before this détente, the situation was far more volatile.
In December 1985, retired Air Chief Marshal Muhammad Anwar Shamim revealed that Pakistan had prepared plans in 1984 to strike India’s Bhabha Atomic Research Centre at Trombay if Kahuta Nuclear Laboratory came under attack. At the time, Pakistan was still a dozen years away from acquiring nuclear weapons, and fears of Indian pre-emptive action loomed large. Shamim’s 1985 address at the Institute of Strategic Studies Islamabad (ISSI) hinted that Pakistan’s newly acquired F-16s were “Pakistan’s nuclear option minus the nuclear bomb”.
American scholar Dr Robert Wirsing, who attended Shamim’s lecture, later described how the air chief had made it clear that the F-16s were selected specifically for their ability to reach deep into Indian territory and strike nuclear assets in retaliation. Shamim confirmed in his 2010 memoir Cutting Edge PAF that India was warned through diplomatic channels that any attack on Kahuta would result in devastating retaliation against Trombay.
Shamim wrote that Kahuta’s location—just three minutes from the Indian border—rendered it practically indefensible. General Zia-ul-Haq had asked Shamim how to defend this vital facility, and the answer was clear: acquire advanced aircraft to deter India by threatening retaliation. Eventually, the U.S. supplied F-16s after rejecting alternatives like the F-5. In January 1983, Pakistan received its first F-16s, and Shamim wrote to Zia, assuring him that India would now refrain from attacking Kahuta, knowing the potential cost.
Shamim even sent a warning to the Indian scientific community via Munir Hussain, Secretary of Science and Technology, who conveyed to his Indian counterpart the devastating consequences of any attack on Pakistani nuclear assets. “No brother, we know your capability and we will not undertake such a mission,” the Indian official reportedly replied.
Implications for Pakistan and India
When Washington preached the value of the nuclear taboo, the rest of the world followed. Now that the U.S. has shattered it with impunity, others may feel free to follow suit. This is particularly concerning in South Asia, where tensions between India and Pakistan remain high. Indian Prime Minister Narendra Modi has stated that future responses to cross-border terrorism may be more severe, and that such responses will not distinguish between terrorists and their supporters. Meanwhile, Pakistan’s Chairman Joint Chiefs of Staff Committee, General Sahir Shamshad Mirza, has vowed that Pakistan’s response in case of war would “cover the whole of India”.
Interestingly, despite the heated rhetoric, both nations showed significant restraint during the May 2025 Four-Day War. India avoided hitting Pakistani military installations or crossing into Pakistani airspace. Pakistan, in turn, limited its strikes to Indian military targets near the border. Neither side attacked the other’s strategic core.
In this context, Mark J. Massa’s thesis—that attacks on nuclear installations using conventional weapons will not lead to nuclear escalation—seems dangerously misplaced in the South Asian context. Both Pakistan and India possess diverse, dispersed, and survivable nuclear arsenals. A limited conventional attack is unlikely to disable either side’s deterrent. But it may provoke a nuclear response.