Oh come on. South Vietnam was an American client state from the word go. American advisors helped run Ngo Dinh Diem's campaign in the 1955 referendum that set up the South Vietnamese government. When Diem didn't turn out to be the man the U.S. government had hoped he would, American money helped finance the 1963 coup that killed him.
> and never did actually invade North Vietnam
No, we just bombed the holy hell out of them: see Operation Rolling Thunder (http://en.wikipedia.org/wiki/Operation_Rolling_Thunder) and Operation Linebacker II (http://en.wikipedia.org/wiki/Operation_Linebacker_II) for examples.
There was still no invasion of Vietnam. The entire operation was hamstrung by politically imposed restrictions.
"We weren't any worse than the soviets" is not a moral defense, and given that we couldn't hold south vietnam against insurgency, you'd need a hell of a case to support the idea that we could have held north vietnam.
I mean, given that we were dropping napalm and agent orange, what kind of "politically imposed restrictions" would you say held us back from winning?
The war effort was also politically micromanaged--for instance, every airstrike had to be individually approved by the White House. This led to delays and, frankly, interference in military affairs from incompetent politicians.
Fighting a counterinsurgent war on the defensive is never strategically sound; one is always better served by being on the move and taking the initiative. This was politically impossible in Vietnam, which is why it took so long.
Now, perhaps there were valid political reasons not to invade north Vietnam. In that case, the answer is not to get involved at all. You either do the job right or you don't do it at all. In either case, the mistake wasn't that the US invaded Vietnam without a good reason--there was no invasion, and there was a good reason. The mistake was that the US didn't fully commit to the objective, and that the White House didn't let the military do their job.
Here's the fact: Nobody wanted us there. South vietnamese were informing on the US and killing our troops. You think having a few airstrikes being more effective would have made a difference for that? Like if we just killed enough of the bad guys, the rest of them would have given up?
That's not the way asymmetrical warfare works. Every guy you kill has brothers and cousins who want to avenge him. Losing the political battle is losing the war. That's why we won in Iraq (Al Qaeda in Iraq were flown-in nihilists who alienated the population), and that's why we're losing in Afghanistan (the Taliban are a local movement with a local base).
You're seriously saying that had we invaded North Vietnam and bombed more stuff, it would have been fine? Like we could cut the supply of an army that was living off the land? Looks like we would've just been occupying twice as much ground with the same number of troops, unless you're advocating killing every last man, woman and child in the country.
And no military can be effective when it's micromanaged from the White House.
If you're living off the land, conducting guerilla warfare, you can't be broken. "Broken" is for standing armies. Guerillas just leave the field of battle and then bomb your patrols when you try to occupy.
http://en.wikipedia.org/wiki/Arrest_and_assassination_of_Ng%...
I didn't say the people of South Vietnam democratically voted to formally request US involvement, or that the Diem regime was morally legitimate, or even that it was a good idea to get involved in the Vietnam War. Just that there was no actual invasion anywhere in the process.
A bit of revisionist history never hurt anyone.