WASHINGTON — A growing number of U.S. intelligence, defense and diplomatic officials have concluded that there's little hope of preventing nuclear-armed Pakistan from disintegrating into fiefdoms controlled by Islamist warlords and terrorists, posing the a greater threat to the U.S. than Afghanistan's terrorist haven did before 9/11.

" Pakistan has 173 million people and 100 nuclear weapons, an army which is bigger than the American army, and the headquarters of al Qaida sitting in two-thirds of the country which the government does not control," said David Kilcullen , a retired Australian army officer, a former State Department adviser and a counterinsurgency consultant to the Obama administration.

The experts McClatchy interviewed said their views aren't a worst case scenario but a realistic expectation based on the militants' gains and the failure of Pakistan's civilian and military leadership to respond.