President Pervez Musharraf of Pakistan says there is a "zero percent chance" of al-Qaeda getting hold of his country's nuclear weapons.
In an address to a French foreign policy institute, he stressed it was impossible for militants to gain any access to Pakistan's nuclear arsenal.
Mr Musharraf is on an eight-day visit to Europe, with democracy and tackling terror high on the agenda.
He said he believed Pakistan elections in February would be free and fair.
The president said that the only way for militants to gain access to Pakistan's nuclear arsenal would be if al-Qaeda or the Taleban "defeated the Pakistani army entirely" or if extremist religious groups won next month's elections.
"There is a zero percent chance of either one of them, they (the weapons) cannot fall into any wrong hands," he said.
"We don't think it is possible that this al-Qaeda or Taleban can take over in Pakistan. We cannot be defeated like this."
President Musharraf was speaking as Pakistani forces said they had killed 37 pro-Taleban militants in overnight clashes in the tribal region of South Waziristan adjoining the Afghan border.
Pakistan has a number of nuclear-capable missiles
"We are succeeding reasonably," in securing the border with Afghanistan, he said, pointing out that there had been a 42% reduction in movement across the frontier because of the creation of 1,000 checkpoints.
The president played down recent violence by pro-Taleban militants in North and South Waziristan, saying they were "pinpricks" his government could fully deal with.
"There is no Taleban offensive... being launched," he said.
"These are pinpricks that they keep doing - and we have to manage all of that."
Mr Musharraf said that he was "not concerned" about political turmoil at home following the assassination of Benazir Bhutto last month, and insisted his country was stable.
"I can assure you that nothing will happen in Pakistan," he said. "We are not a banana republic."
The president said it was "unfortunate" that a 15-year-old boy had been arrested last week on suspicion of being among one of those involved in the killing of Ms Bhutto in a gun and suicide attack.
He said that the teenager had been "indoctrinated" by Baitullah Mehsud - a militant leader in South Waziristan who Pakistani authorities and the CIA say masterminded the attack on the former prime minister.