U.S. commanders are worried that if they had to head off a conflict with Russia, the most powerful military in the world could get stuck in a traffic jam.

Humvees could snarl behind plodding semis on narrow roads as they made their way east across Europe. U.S. tanks could crush rusting bridges too weak to hold their weight. Troops could be held up by officious passport-checkers and stubborn railway companies.

Although many barriers would drop away if there were a declaration of war, the hazy period before a military engagement would present a major problem. NATO has just a skeleton force deployed to its member countries that share a border with Russia. Backup forces would need to traverse hundreds of miles. And the delays — a mixture of bureaucracy, bad planning and decaying infrastructure — could enable Russia to seize NATO territory in the Baltics while U.S. Army planners were still filling out the 17 forms needed to cross Germany and into Poland.