I think this is about right -- we have to keep fighting the war on terror, but here, not overseas:
But President Bush was right about this much: “The Middle East will either become a place of progress and peace, or it will be an exporter of violence and terror that takes more lives in America and in other free nations.” About that there can be little doubt — but what are we to do about it?
[. . .]
President Bush was not wrong in his desire to take the fight to the enemy; this was, in fact, an admirable inclination. But a more effective and prudent strategy would be to exclude the enemy rather than seek him out. Our main interest in Iraq and Afghanistan was terrorism, and terrorism can be contained by means other than pitched battles and infantry divisions.
[. . .]
The campaigns in Iraq and Afghanistan are lost or are going to be lost; Americans do not have the stamina for those fights. But those campaigns are not identical to the campaign against terrorism, which we continue, resolutely and inexplicably, to refuse to fight on the most critical fronts: on the borders and at the airport immigration windows. The attacks of 9/11 were carried out by men with box cutters, and it is not beyond imagining that those who wish us ill might consider the lawlessness that prevails to our south and figure out which way on the compass is north.
The biggest lesson I took from Vietnam was that America shouldn't start wars it wasn't able or willing to finish, wasting money and throwing away lives for no purpose whatsoever -- the "oops, didn't reallty mean it" school of foreign policy. So naturally my instinctive reaction to Iraq's descent into chaos in our absence was a disheartened "Here we go again."
But everybody knos -- or should anyway -- that when we leave places, conditions revert to what they were before we were there. Nixon and Kissinger understaood that about Vietnam, and Obama et al. surely know it about Iraq and Afghanistan. That's no reason to re-engage, however.
The only conceivable reason to go to Iraq or Afghanistan was to thwart the spread of terrorism. That battle is best waged right here. Yes, bugging out the way we do lately makes us seem weaker as a country and encourages our enemies. But that's an argument to be careful what we start, not one to justify re-entering a war we've already lost.