Since 1966, over 630,000 men, 100,000 tons of foodstuffs, 400,000 weapons and 50,000 tons of ammunition had traveled through the maze of gravel and dirt roads, paths and river transportation systems that crisscrossed southeastern Laos. The trail also linked up with a similar logistical system in neighboring Cambodia known as the Sihanouk Trail. However, following the overthrow of Prince Norodom Sihanouk in 1970, the pro-American Lon Nol regime had denied the use of the port of Sihanoukville to communist shipping. Strategically, this was an enormous blow to the North Vietnamese effort, since 70 percent of all military supplies that supported its effort in the far south had moved through the port. A further blow to the logistical system in Cambodia had come in the spring and summer of 1970, when U.S. and ARVN forces had crossed the border and attacked PAVN/VC Base Areas during the Cambodian Campaign.