Pakistani Prime Minister Yusuf Raza Gilani said Monday that his country's nuclear weapons are well-guarded, rebutting misgivings by nuclear experts about the safety of the small but growing arsenal.
"Islamabad has taken effective steps for nuclear safety, security and nonproliferation through extensive legislative, regulatory and administrative framework," said Gilani, who was in Washington for a historic 47-nation nuclear security summit.
A new report from a Harvard nonproliferation expert, released Monday, finds that Pakistan's stockpile faces "immense" threats and is the world's least secure from theft or attack.
President Barack Obama is hosting the summit, which he hopes will help him reach his goal of ensuring that all nuclear materials worldwide are secured from diversion within four years.
Obama is trying to persuade world leaders to confront the threat that nuclear arms might fall into the hands of terrorists, a possibility he describes as the biggest threat to global security.
Pakistan's leaders insist their stockpiles are safe and contend their country follows the regulations set by the International Atomic Energy Agency.
"We are confident our system is second to none," said Foreign Minister Shah Mahmood Qureshi. "We have world-class measures in place."
The study, commissioned by the Nuclear Threat Initiative and released by Harvard University's Belfer Center for Science and International Affairs, found that Pakistan faces formidable risks in safeguarding its nuclear warheads.
While acknowledging substantial security improvements in the last few years, the study notes that the danger persists from "nuclear insiders with extremist sympathies, al-Qaida or Taliban outsider attacks, and a weak state."
Experts said Pakistan and its nuclear-armed neighbor, India, appear to be minimizing the threat.
"Unfortunately, I do not see this concern either in Pakistan or India about nuclear terrorism," said Pakistani physicist Pervez Hoodbhoy, who attended a parallel, unofficial conference of more than 200 international nuclear experts. "Both countries do not see the seriousness of this situation."
American nonproliferation expert Robert Gallucci told the same conference he believes it is probable over time that terrorists will detonate an atomic weapon in a city somewhere, not necessarily in the United States or Europe.
Clearly with Pakistan and India in mind, the former U.S. diplomat said, "Any country that has suffered serious terrorist attacks, foreign or domestic, needs to take this threat seriously."
AP Special Correspondent Charles J. Hanley contributed to this report.