Last year, Pakistan experienced a wave of leadership transitions. The country welcomed a new government, president, Supreme Court chief justice, and army chief.

Yet one of the most troubling changes occurred on the very last day of 2013, and with little fanfare. On December 31, according to Pakistani media reports, Lt. Gen. Khalid Kidwai logged his last day as head of the Strategic Plans Division (SPD), the entity in charge of Pakistan’s nuclear weapons.

Kidwai has long been the institutional face of Pakistani nukes. The SPD was established in 2000, and Kidwai has been its only director (he’s been described as the “longest serving boss in any strategic or defense establishment” in Pakistan). He received numerous extensions to continue in the post after 2007, the year of his formal retirement.

Kidwai garnered high praise for his work. Pakistani patriots may revere him for presiding over a drastic expansion of the nation’s nuclear arsenal, but international security experts laud him for his leadership—as well as for improving security at sensitive sites. In the words of South Asia security specialist Michael Krepon, “his competence inspires the view that he is indispensable.”

It’s this longevity and success that make Kidwai’s departure so unsettling. For all his accomplishments, volatile Pakistan remains deeply nuclear-insecure. This is a country where one nuclear scientist—AQ Khan—sold nuclear secrets to pariah states, and another—Sultan Bashiruddin Mahmood—talked nukes with Osama Bin Laden just weeks before the 9/11 attacks. Where, according to U.S. intelligence, scientists with sympathy for Islamic radicalism have sought positions in the nuclear sector. And where, according to a report in The Atlantic, nuclear bombs are transported via “delivery van” on “congested and dangerous” roads.

Little wonder that five years ago, a U.S. Congressional investigation predicted a nuclear or biological attack by the end of 2013—with a strong likelihood that it would originate in Pakistan. And little wonder that documents made available by NSA whistleblower Edward Snowden last year revealed that a nervous Washington is expanding its surveillance of Pakistan’s nuclear weapons.

Pakistan’s nuclear insecurity is intensified by its nuclear strategies. The country is rapidly expanding its stockpile; it now boasts one of the world’s fastest-growing arsenals. The more nuclear weapons, the greater the risks. Additionally, Pakistan is emphasizing the production of tactical nuclear weapons (TNW). Generally speaking, these weapons are meant for actual battlefield use with conventional forces (and in Pakistan’s case, for short-range use against India). Consequently, they may be removed from locked-down and secured bases, making them tremendously vulnerable to seizure, attack, or accident.

Indeed, because of this vulnerability, TNWs are a favorite target for terrorists. Such an attack is certainly plausible in militancy-ravaged Pakistan, where extremists have recently assaulted military bases thought by some to house nuclear weapons. In 2012, security authorities acknowledged a “serious threat” from the Pakistani Taliban to attack one of Pakistan’s largest nuclear installations.

All of this begs the question: Is anyone other than Khalid Kidwai capable of managing Pakistan’s nuclear security challenges, given their sheer magnitude?

To be sure, many would say yes. Kidwai’s replacement, Lt. Gen. Zubair Mahmood Hayat, is a protégée of former army chief Ashfaq Parvez Kayani. Pakistan’s security establishment repeatedly commends his professionalism. One recent Pakistani media report, citing military sources, describes Hayat as “brainy, brave, and bold.”

Others would argue that the SPD’s institutional strengths render irrelevant any questions about the capabilities of its leaders. Many international observers praise the office for its effectiveness. Significantly, the SPD has created institutional mechanisms that, in the words of one nuclear expert, “can handle a baton pass.” As Feroz Khan, a former senior SPD official, put it to me in a recent conversation, Kidwai’s departure “reflects institutional maturity rather than [a] personality-driven system.”

Fair enough. But let’s face it: Strong leadership matters, especially during crises. Most historians don’t credit the National Security Council for allowing the world to survive the Cuban Missile Crisis; they credit the leadership of President John F. Kennedy.

Few countries are as prone to a nuclear crisis as Pakistan—and this threat could well rise in the next year. The withdrawal of international forces from Afghanistan portends heightened competition between Pakistan and India for influence in Afghanistan. The U.S. troop withdrawal also deprives militants of a prime target, increasing the likelihood that some jihadists—including those with ties to Pakistan’s security establishment—will launch new campaigns of violence in India. These scenarios could dangerously escalate India-Pakistan tensions, and conceivably trigger armed mobilizations that include TNWs.

A nuclear crisis in Pakistan could also have devastating consequences for the United States. “What happens or fails to happen in Kidwai’s modest compound,” the New York Times’ David Sanger wrote several years ago, “may prove far more likely to save or lose an American city” than the billions the United States spends on its own nuclear arsenal.

Clearly, the stakes are high. Hayat seems an exceptionally capable leader, and he’ll likely be successful. Nonetheless, we have good reason to be anxious about the departure of Kidwai, the long-serving nuclear weapons czar who brought a small measure of stability to one of the world’s foremost flashpoints.

Michael Kugelman is the senior program associate for South Asia at the Woodrow Wilson International Center for Scholars in Washington, DC. Follow him on Twitter: @michaelkugelman.

Image: Wikipedia/Wikcommons.