There is an old military adage: amateurs talk tactics, professionals talk logistics. For an occupying power seven thousand miles from home, logistical problems can be especially acute. Currently, America has two re-supply routes for its forces in Afghanistan, both of which transit Pakistan. The most heavily used route goes through the heart of Taliban power in the Federally Administered Tribal Areas and across the Khyber Pass.
Over the past few months, Taliban attacks on NATO supply convoys have markedly increased. The Pakistani government has repeatedly been forced to close the Khyber Pass temporarily while they attempt (and fail) to crack down on militants in the area. While this began as a minor headache, the problem has grown. Meanwhile, America's forces in Afghanistan are set to increase under Barack Obama.
One option for a new supply route is through Iran. Hard as it is to believe, a reconciliation with Iran is hardly out of the question, and Iran materially supported our overthrow of the Taliban. Nevertheless, Iran would not be a short-term solution and America would be hesitant to give Tehran such a great degree of leverage before negotiations over Iraq and Iran's nuclear program have been settled.
Another option is a northern route, through Central Asian territory and perhaps Russia. However, with Moscow flexing her muscles in her near abroad, and America supporting resistance in a wide arc from Estonia to Georgia and beyond, the price for a re-supply route would not be cheap: likely Ukraine. As Stratfor correctly notes: "there is too much at stake, and the window of opportunity is too narrow for Moscow to simply play nice with the new American administration without a much broader strategic agreement and very real concessions."
“There have been agreements reached, and there are transit lines now and transit agreements for commercial goods and services in particular that include several countries in the Central Asian states and also Russia,” [Petraeus] said.
What was the price? Are the new supply routes worth the cost? I don't know. I'll update once Stratfor publishes an analysis.