Apparently it wasn't Napoleon who said an army travels on its stomach. But surely the necessity of providing appropriate gear, food, water and other basics to troops was clear after his troops, freezing and dropping from starvation, staggered in retreat after the disastrous 1812 invasion of Russia. Of the 680,000 men Bonaparte took with him, fewer than 100,000 returned. Perhaps nothing that dramatic is about to happen in Afghanistan. But the warning signs of impending trouble are clear: the $57 billion U.S. investment in Afghanistan's security forces is at risk because the Afghans cannot supply, or resupply their troops, can't prevent their weapons and vehicles from breaking down and can't fix them when they do.