Route 9 Problem
When the North Vietnamese Army (NVA) planned to send forty thousand troops to attack the six thousand US Marines at Khe Sanh in 1968 it expected a decisive victory. Certainly, the small US Special Forces camp in the way at Lang Vei would be quickly overcome.
The tough, tenacious defenders at Lang Vei had other ideas. The two dozen US Army Green Berets and their four hundred tribesmen at Lang Vei gave the NVA such a monumental headache that they became known as the "Route 9 problem" all the way to the highest levels of the North Vietnamese government. Even the NVA's tanks--their first use in the war--couldn't completely defeat the stubborn US fighters.