Quote Originally Posted by Bob's World
None of these insurgencies "required" massive foreign support
Firstly, the North Vietnamese war effort depended upon Soviet and Chinese support, which also involved interference in Cambodia and Laos that enabled the North Vietnamese to use those countries as lines of communication and staging areas. North Vietnam did not have an industrial base of any significance, and depended on the Soviets and Chinese for everything from small arms and ammunition, to artillery, aircraft and advanced air defense systems.

Hundreds of thousands of Chinese and Soviet volunteers and advisors (~300,000) served in North Vietnam, operating air defense radars, SAM sites, transporting materiel, training North Vietnamese forces and even participating in combat as volunteers with the NVA (esp. pilots). By the time of Johnson's escalation, North Vietnam had developed one of the world's densest and most advanced IADS' in the world. The Soviets and Chinese competed with one another to replace North Vietnamese losses faster...

Secondly, the Afghan Taliban depended upon the support of their brethren in Northern Pakistan for logistics, staging areas, arms and ammunition. They also received the support of sympathetic members of the Pakistani government, and in particular the ISI, who kept the Durand Line porous and the weapons and fighters flowing.

Thirdly, Iraq was certainly awash in weapons and ammunition in 2003 after the fall of Hussein. However, Syria sent Islamist fighters to Iraq to join the Sunni Arab insurgency and the Iranians provided arms to the Shia militias, in addition to inserting members of the Quds force.

Quote Originally Posted by Bob's World
...but if we create an insurgency and dedicate ourselves to grappling with it, our opponents will certainly leverage our stupidity to their advantage.
This is certainly true.

An insurgency in southern Afghanistan was inevitable given the stateless Pashtun nation astride the border with Pakistan, the subversion of Pashtun nationalism into fierce Islamism and Pashtun disdain for the ethnic and religious groups of northern Afghanistan. The notion that they would accept rule from Kabul and would have greater affinity for the polyglot north rather than the Pashtun of northern Pakistan was ludicrous. The country needed to be divided at least internally, with the south having considerable autonomy bordering on independence.

Again, de-Ba'athification assured that the Sunni Arabs of Iraq would fight against the perceived threat of Shia domination and vengeance, and the Americans were considered in league with the Shias.