Pakistani President Pervez Musharraf has put the country's nuclear weapons under the control of the president, rather than the prime minister.
Pakistan has several nuclear-capable missiles
The president issued an ordinance - which has to be ratified by parliament some time over the next six months - which formalised his control on Friday.
His move comes amid concern abroad that the nuclear arsenal could fall into the hands of Islamist extremists.
The military says that its nuclear weapons security is "foolproof".
President Musharraf assumed control of his country's nuclear weapons by taking command of the National Command Authority (NCA), the body which is responsible for operating them.
In 2004 AQ Khan admitted to passing nuclear secrets
General elections are due to be held in Pakistan on 8 January and many commentators predict that if the vote is fair, a government hostile to President Musharraf could emerge.
Army spokesman Maj Gen Waheed Arshad said there was a consensus among political parties in Pakistan that nuclear weapons should be controlled by the NCA.
He said it was important that the make-up of this body should be put on a firm legal footing before the elections.
"There is a transition in process and the country is returning to full democracy, so whatever things were left to be done are being done," he said.
The security of Pakistan's nuclear arsenal has been of worldwide concern in recent months because of spread of pro-Taleban militancy.
The president has temporary control of the nuclear arsenal
President Musharraf established the NCA in 2000, two years after Pakistan detonated several atomic devices to establish itself as the Islamic world's only declared nuclear weapons power.
Four years after the first tests, the country's top nuclear scientist, Abdul Qadeer Khan, was exposed as the head of an international black market in nuclear technology.
Today Pakistani officials remain sensitive to suggestions that Pakistan's nuclear weapons - the country's main source of defence against arch-rival India - might not be under firm control.
Last month the authorities strongly condemned suggestions by two American academics that American forces could enter Pakistan to prevent radical militants Islamists from getting their hands on a nuclear device.
"The NCA took note of the hostile campaign in a section of the international media with regard to Pakistan's nuclear assets," said a statement on Friday.
"While reiterating that the security of Pakistan's nuclear assets was foolproof, it advised against creating irresponsible alarm."
The statement said that Pakistan was capable of defending its interests and cautioned those "contemplating misadventures".
Last month Pakistan confirmed that the US was helping ensure the security of its nuclear weapons.