Uncertainty over who is actually in charge in Pakistan has heightened concerns over the country's nuclear arsenal, which is today variously estimated at 50 to 100 nuclear weapons.
While U.S. officials say publicly they are confident it is secure, in private they have long harbored worries about what would happen when Musharraf no longer stood atop the country's nuclear command structure, which has always been a creation of Musharraf himself. How robust it will prove without him, they say, is a worrisome mystery.
Perhaps the greatest concern is what one senior Bush administration official recently termed "steadfast efforts" by the extremist groups to infiltrate Pakistan's nuclear laboratories, the heart of a vast infrastructure that employs tens of thousands of people. Some of the efforts, officials said, are believed to have involved Pakistani scientists trained abroad.
Pakistan's weapons are considered less of a concern - thanks in part to a secret program launched by the Bush administration, with Musharraf's consent, to help train Pakistani security forces to keep the weapons safe.
In announcing his resignation, from his presidential office here at 1 p.m., Musharraf said he was putting national interest above "personal bravado," adding that he was not prepared to put the office of the presidency through the impeachment process.
The chairman of the Pakistani Senate, Muhammad Mian Soomro, who had served as caretaker prime minister earlier this year, was named acting president. He will keep the office until a new president is chosen by the parliament and four provincial assemblies within 30 days.
Zardari, the widower of Benazir Bhutto and now the head of the Pakistan People's Party, is known to want the job. But he remains something of a controversial figure here, having faced multiple counts of corruption in the past, though he was never convicted and says the charges were politically motivated. They were dropped when Zardari returned to Pakistan earlier this year.
