Moving the mountain of military gear out of Afghanistan after more than a decade of war will cost billions of dollars and prove far more difficult than last year’s withdrawal from Iraq, the Pentagon’s No. 2 official said Tuesday.

Deputy Defense Secretary Ashton Carter, the Pentagon’s point man for overseeing the draw down in Afghanistan, talked about the challenges in his first extensive interview on pulling out of Afghanistan.

The pace of withdrawal is picking up: About 20,000 U.S. troops and their gear will be coming home by October. There are about 88,000 American forces there now. All U.S. combat forces are to leave by 2014. Meanwhile, the main overland supply route through neighboring Pakistan reopened last week. It had been closed since November after U.S. forces mistakenly killed 24 Pakistani troops on the border.

“It’s a very austere logistics environment to transport anything,” Carter said. “Combat is still going on. Terrible terrain. Narrow roads. Long way to a seaport. Afghanistan is orders of magnitude more challenging for … [withdrawal] than was Iraq.”Click here to read more