OK, we need a show of hands.

How many out there think the main problem with the United States’ experience in Vietnam was that we didn’t stay there long enough?

Everyone who agrees, stand over there with President Bush.

Especially with the departure of Alberto Gonzales, he needs some company.

Last week, speaking to the Veterans of Foreign Wars in Kansas City, the president unveiled his latest justification for fighting the Iraq war. If the United States left Iraq, he argued, it would have the kind of disastrous impact that the United States leaving Vietnam had.

For those of you keeping track at home, this is at least the fourth explanation of the United States’ presence in Iraq.

First, it was because Saddam Hussein had weapons of mass destruction that he might use at any moment against America. We were warned that the smoking gun could turn out to be a nuclear cloud.

After that didn’t turn out, the Bush administration explained that the real point of the war was to create a Jeffersonian democracy in Iraq that would serve as a beacon for the entire Middle East. Every election was hailed as a historic development, until it became clear that the elections weren’t actually producing, um, working governments.

Then we were told we were in Iraq to fight al-Qaida, “the people who attacked us on September 11,” even though al-Qaida in Iraq didn’t exist then, and most of the attacks on U.S. forces are from Shiites, bitter enemies of the Sunni al-Qaida.

And now Bush assures the Veterans of Foreign Wars that we have to fight in Iraq because, as in Vietnam, it would be bad if we leave.

“Then as now,” the president declared solemnly, “people argued that the problem was America’s presence and that if we would just withdraw, the killing would end.”

Instead, there was a bloody and brutal episode following our departure, so we shouldn’t have left.

And that’s why we should stay in Iraq, which also reminded the president of Korea and World War II.

It’s never safe to let George Bush alone with a historical comparison, but Vietnam is an especially awkward one for him. It’s not so much that he and Vice President Cheney so energetically sought to avoid going to Vietnam – a lot of us did that – as that they never seemed to notice the war.

Not how bitterly it divided the United States, or how impossible a victory seemed after 15 years, 58,000 U.S. deaths and millions of Vietnamese casualties. If the president is looking for a model for the Iraq war that he seems to want to fight indefinitely, he might have to look a little further.

Not that Bush seemed to have any ideas on how the Vietnam War might have been won. He just thinks we should have kept fighting it.

Actually, there are some useful points from our Vietnam experience. There’s a message that if the local government you’re fighting for doesn’t work, it doesn’t matter how long you keep fighting. There’s the lesson that when the American people decide they’ve given up on a war, it’s hard to keep it going.

And the overall message that a war you fight in a society you don’t understand is unlikely to turn out well.

The time to remember what we learned from Vietnam isn’t four years into the Iraq war. The time to remember Vietnam was four years ago.

Which is why Americans, after Vietnam and Iraq, find it hard to invest unlimited lives and billions into the president’s cheerful forecast: “A free Iraq will be … an example that provides hope for millions throughout the Middle East, it will be a friend to the United States, and it’s going to be an important ally in the ideological struggle of the 21st century.”

He sounds like he hasn’t noticed either war.

Still, in the president’s look back at the impact of Vietnam, and the world’s response to it, there’s at least one point hard to dispute: If we had refused to leave Vietnam until we won that war, we wouldn’t be in Iraq today.

Because the U.S. Army would still be in Vietnam.