Why has U.S. allowed Taliban 'free rein' in Pakistan?

In McClatchy's, here

"...For seven years, the Bush administration has pursued al Qaida but done almost nothing to hunt down the Afghan Taliban leadership in its sanctuaries in Pakistan, and that's left Mullah Mohammad Omar and his deputies free to direct an escalating war against the U.S.-backed Afghan government.

The administration's decision, U.S. and NATO officials said, has allowed the Taliban to regroup, rearm and recruit at bases in southwestern Pakistan. Since the puritanical Islamic movement's resurgence began in early 2005, it's killed at least 626 U.S.-led NATO troops, 301 of them Americans, along with thousands of Afghans, and handed President-elect Barack Obama a growing guerrilla war with no end in sight.

From Baluchistan, Omar and his council are believed to direct the Taliban's broad military and political strategies and to arrange arms and other supplies for their fighters in southern Afghanistan, U.S. officials said.

They preside over military, intelligence, political, and religious committees, and also oversee a fund-raising operation in the Pakistani port city of Karachi that raises money across the Muslim world, said a Pentagon adviser on the region, who asked not to be further identified.

Baluchistan also is a major corridor through which Afghan opium, which is refined into heroin, is smuggled to the outside world, providing the Taliban with $60-$80 million a year..."