President Asif Ali Zardari has ceded his position in Pakistan's nuclear command structure to his prime minister, in a sudden political maneuver widely seen as a fresh sign of turmoil on the eve of President Barack Obama's strategy announcement for the region. The move, announced in a news release late Friday night, was an all-out attempt to head off domestic political pressure as Zardari's two-year presidency hit a new low. With the end of a political amnesty program on Saturday, Zardari and his allies now face potential corruption and criminal charges, and the opposition is demanding that he relinquish many of his powers or resign. Although analysts did not expect the move to harm Pakistan's nuclear security, any change to political stability in the country is critical for the Obama administration, which is set to announce its new strategy for Afghanistan this week. Pakistan is a central part of that strategy, and the country has been under tremendous pressure by the administration to step up its fight against militants from the Taliban and al-Qaida, with two top American security officials visiting Pakistan's capital, Islamabad, in two weeks. Until his latest move, Zardari held the top civilian position in the organization known as the National Command Authority, which controls every aspect of Pakistan's nuclear arsenal -- decisions to move or launch any of its 60 to 100 nuclear weapons, to expand the country's nuclear stockpile and to oversee the security of the weapons and nuclear laboratories. Pakistan's previous president, Pervez Musharraf, was an army general, and Zardari's position was supposed to signal civilian control of the country's nuclear assets. But in reality, it is Pakistan's powerful military that exerts control over the country's nuclear arsenal, and Pakistani observers noted Saturday that the handover to Prime Minister Syed Yousaf Raza Gilani had no practical effect on the hierarchy. 'Nothing changes except that Zardari has removed one possible irritant with nuclear hawks,' said a Pakistani official, who spoke on the condition of anonymity because he was not authorized to speak about nuclear issues. The military establishment dislikes Zardari and has an acrimonious history with his party, the Pakistan People's Party. A senior party member said the move was an attempt to restore a strong-Parliament system that had been disrupted under Musharraf's rule. In most nuclear-weapons nations, it is the civilian leadership, not the military, entrusted with nuclear control. But 62-year-old Pakistan has always been an exception. Its military has always been more powerful than its weak civilian governments, and U.S. officials have always taken some solace that the military oversaw all elements of the nuclear program. Some here argue the military wants it to stay that way. It protested vociferously when the Obama administration, which has said it wants to support democratic institutions here, extended a large civilian aid package to Pakistan this fall, the first in the history of the two countries. The move seemed to say more about Pakistani politics and Zardari's attempts to survive as president, than about the country's nuclear arsenal. Zardari is at his most vulnerable since taking office, and is looking for ways to appease his critics. But many political analysts say he will not survive if he does not address the opposition's main criticism -- that he has yet to give up the sweeping powers he inherited from Musharraf, such as the right to dismiss elected governments, abnormal in a parliamentary system like Pakistan's. Friday's move did nothing to relinquish those powers, and as a result, was largely ignored in the Pakistani news media. But the senior party member said Zardari would start giving up those powers in a process that would begin next month. And it was not clear on Saturday whether handing control to Gilani would have any effect in terms of blunting criticism. Gilani is a mild-mannered politician from Pakistan's most populous province, Punjab. He is a member of Zardari's party, but is believed to be more palatable to the country's powerful military establishment. Most Pakistani analysts rule out a military coup, but the news media has been talking for months about a 'minus one' scenario, under which Zardari would step down, and another member of his party would assume the post. Zardari's supporters say that is highly unlikely. The opposition leader, Nawaz Sharif, is also a crucial player, whose support could allow Zardari to remain in power. His party has repeatedly called for a repeal of the Musharraf-era powers, and Zardari's delays in doing so could turn Sharif against him, making Zardari's resignation all but inevitable. From the start of Zardari's term, U.S. officials have worked hard to cultivate alternate contacts within Pakistan -- including Sharif and Gen. Ashfaq Parvez Kayani, the chief of Pakistan's military -- tacitly acknowledging the complex and volatile nature of the country's politics. In practice, it is the military that has always controlled most of the nuclear decisions in the country. Its top officers dominate the National Command Authority and its major decisions. Many of the day-to-day operations, including those most of concern in Washington, concerning nuclear security, are made in a small compound near the Islamabad airport by the Special Plans Division, run by Gen. Kahlid Kidwai. Kidwai was appointed to his position by Musharraf, who took control of the country in a coup in 1999 and resigned, under pressure, more than a year ago. Together the two men established much of the country's nuclear infrastructure, and it was telling that Kidwai remained in place after Zardari took office as the country's elected president. It also suggested that, save for the names on an organization chart, little changed in practice. And military control did not prevent Pakistan from becoming the source of the most egregious case of nuclear proliferation in modern history: the sale of the country's nuclear technology by Abdul Qadeer Khan, a metallurgist who created a black market for nuclear technology and sold it to Iran, North Korea and Libya, and perhaps other nations. Of all the institutions in Pakistan, none is of more importance to the Obama administration than the National Command Authority. But it is also the linchpin of the continuing distrust between Washington and Islamabad. For years during the Bush administration, the United States paid more than $100 million to Pakistan to help it secure its nuclear weapons. But U.S. officials never knew exactly how much of the money was spent: Pakistan did not want the United States to know much about its weapons or where they were located, for fear that in times of chaos the Americans would seek to seize the weapons rather than allow them to fall into the hands of terrorists. 