The Pakistani army, backed by attack helicopters, is fighting intense gun battles in the Swat valley 60 miles outside the capital of Islamabad with Islamic extremists.

Al Qaeda and the Taliban have struck back with suicide bombs in Pakistan's major cities, including Lahore. A plot in Karachi was foiled but the extremists vow more carnage is imminent.

The battles are the latest in a deadly struggle for the control of Pakistan. Some are hoping this, at last, is the turning point when the army and the Pakistani government will finally defeat the extremists, but history suggests that conclusion is premature.

More likely, this will be yet another temporary setback for the Islamists, to be followed by new advances elsewhere.

The fighting has cast a spotlight on the shaky security of Pakistan's growing nuclear arsenal — the fastest growing arsenal in the world.

Pakistan is finishing construction of several new reactors and is seeking to buy more from China to increase its production of fissile material. The United States has provided Pakistan with over $10 billion in military aid since 2001.

No one outside Pakistan can say if some of that money was diverted directly to the nuclear program by the army, but undoubtedly the U.S. assistance indirectly made it easier for the army to use its own funds to accelerate the development of its nuclear weapons.

Today the arsenal is under the control of its military leaders; it is well protected, concealed and dispersed. But if the country fell into the wrong hands — those of the militant Islamic jihadists and Al Qaeda — so would the arsenal.

The U.S. and the rest of the world would face the worst security threat since the end of the Cold War. Containing this nuclear threat would be difficult, if not impossible.

The danger of Pakistan becoming a jihadist state is real. Just before her murder in December 2007, former Prime Minister Benazir Bhutto said she believed al Qaeda would be marching on Islamabad in two years.

A jihadist Pakistan would be a global game changer — the world's second largest Muslim state with nuclear weapons breeding a hothouse of terrorism.

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