One interpretation of the Vietnam War that I'm partial to goes like this: however much the United States fought and struggled in South Vietnam, unless they could somehow have hermetically sealed the borders of the country and stopped soldiers and supplies coming in from Communist North Vietnam to support the insurgency in the south, they were always going to lose. On the wall beside me there's a map of south-east Asia from 1965, and on it I can trace the long, permeable border between southern Laos and South Vietnam, running through dense mountains and jungle, posing a similar challenge to Washington's strategists as the Afghan-Pakistan border does now. I can see where Cambodian territory juts almost by design towards Saigon, coming within just a few dozen kilometers of it. That's where the Communists came in, faster than they could be killed.
There's an incredibly tedious historical debate over just how important outside invasion versus homegrown rebellion were as factors in the Vietnam War, although really it ought to have been put to rest by the fact it was four North Vietnamese armoured corps driving straight over the border that eventually put paid to the south. Suffice to say that in the guerrilla war in which so many Americans and South Vietnamese died in the 1960s, the role of men and weapons who came clandestinely over the border from Laos and Cambodia, down the Ho Chi Minh Trail, was very important indeed. These access routes were so obviously important that, at the beginning of the 1960s, the United States nearly went to war to block the route from Laos, recognizing that failing to do so might make the war in Vietnam unwinnable. This, briefly, is that story.
Laos is a landlocked country with a small population that lies west of Vietnam, south of China and north of Cambodia (it's also to the east of Thailand, but the Thai, keeping their heads down as usual, don't feature in our story). Like Vietnam and Cambodia, Laos was colonized by the French in the nineteenth century, and emerged into independence as a result of the war waged by nationalists against the French from 1946 to 1954. While most of the heavy lifting in that conflict was done by the Viet Minh (later Viet Cong), a Communist group called the Pathet Lao also contributed. This group, however, was largely a proxy of the Vietnamese communists, and mostly did as it was told by them. Peace brought a succession of unstable governments to Laos, some involving the communists and some not, and the Viet Minh - now part of the army of independent North Vietnam - never left the country.
The North Vietnamese weren't going to give up their influence in Laos so easily, because they knew how important it could be. In 1959, their rule consolidated at home, the regime in Hanoi started to take more of an interest in the ultimate goal of taking over South Vietnam and reunifying their country under the red flag. To do this, they needed to get men and supplies to a communist movement in the south which was being badly battered by the American-backed regime in Saigon. Having at first tried to truck straight across the border between the two Vietnams but finding the enemy often inconveniently in the way, the North Vietnamese hit on another idea: go through Laos. And this they started to do, in large numbers.
The North Vietnamese were able to do this because of the control they exerted over large parts of Laos thanks to the troops they had there and their virtual control of the Pathet Lao. At the same time, they started to intervene much more belligerently in Laotian politics as well, securing their path to South Vietnam but also endangering the fragile Laotian political settlement achieved in 1954. The Communists started seizing strategic locations throughout the country, and there was growing concern that they intended to take the capital and inaugurate Communist rule, as in North Vietnam. It was widely recognized in America at the time that if this happened, South Vietnam would probably fall and other countries might follow.
At the time, the spread of Communism in south-east Asia was viewed as an aggressive strategy masterminded in China and carried out by the country's lackey, North Vietnam. Just as the Chinese had encouraged North Korea to invade South Korea and then intervened themselves, so they now encouraged North Vietnam to invade its neighbours. There was a sense of inevitability in the Kennedy administration that a decisive war with China had to be fought somewhere, and as Eisenhower had left the Oval Office he had adivsed the younger man to do it in Laos. In fact, the general had said, he would have done it himself if his term in office hadn't been coming to an end as these events unfolded. And so Kennedy was faced early on with a decision: send U.S. troops to Laos to fight North Vietnam and possibly provoke a war with China, who might intervene as they had in Korea, or let the Communists dominate Laos and postpone the fight.
Kennedy didn't choose to fight in Laos for a number of reasons. The first was the Bay of Pigs debacle, which not only made another setback unpallatable but also vastly undermined the president's confidence in the advice of the military and CIA. They told him he could win in Laos, but he no longer believed them. Furthermore, it was clear even to someone who wasn't a military expert that it was much easier to win in South Vietnam - it had a vast coastline which could be used to land U.S. troops, more favourable geography, it was further away from China, and it had a larger and more anti-Communist population. One reason the North Vietnamese had managed to determine the future of Laos so easily was an almost complete lack of martial ability among the Laotians; their combat resembled that of Italian condottieri, mercenary armies who "fought" each other in the Middle Ages mainly for show because they didn't get paid if they got killed. The North Vietnamese, on the other hand, were serious killers. If the U.S. allied with non-Communist Lao, they'd be chaining themselves to a corpse.
So Kennedy instead pushed for a diplomatic settlement in Laos - called "neutralization" - in which Communist and non-Communist forces would go into government together and all foreign troops would be withdrawn. It was, from the start, a sham, and Kennedy himself knew it would be a sham. It was a managed retreat - and, sure enough, after it was signed, the North Vietnamese troops stayed in Laos and the men and supplies kept on flowing down the Ho Chi Minh Trail, where they'd soon start to be used to kill American boys. It wasn't pusillanimity on Kennedy's part, or cowardice - no-one ought to fault a man for refusing to start what would likely have been an unwinnable war. But as a result of his setbacks in Laos and Cuba, Kennedy became even more fixated on the need to defend South Vietnam.
The conditions for the final showdown had been set - but thanks to an assassin's bullet, it would be his successor who had to reap the consequences. If Kennedy had fought in Laos, it's unlikely America's journey through south-east Asian history would have been better - but it would certainly have been different.