The lesson of Vietnam is that we refuse to learn any lessons from Vietnam.
Even to dare mention the lesson of Vietnam is to risk painting oneself as weak-willed and lily-livered — to say nothing about being old enough to actually remember Vietnam.
But I think there was a lesson, no matter how unlearned, nonetheless: We poured troops and weaponry into an unwinnable war in order to prop up a despotic government for reckless and unfounded political reasons — the domino theory, which stated that if we didn't defeat the communists in Vietnam, we would someday be battling them on the Golden Gate Bridge.
As it turned out, after the deaths of more than 58,000 U.S. combat troops, we lost the Vietnam War and evacuated our embassy employees off the embassy roof in Saigon by helicopter in April 1975, in one of the most humiliating film clips in U.S. history.
The dominoes did not fall. Vietnam has bought nearly $2.5 billion worth of U.S. goods so far in 2014. The Red menace is now our Red trading partner.
So it goes. Having "left" Iraq after the deaths of 4,500 U.S. troops and an incredible $2 trillion spent, we are now heading back to prop up a murderous despot, who has carried out a religious war against his enemies in part by using U.S. arms.
Actually, we never totally left Iraq, because we built the biggest, most expensive embassy in the world there, which employs 5,500 people. By comparison, the White House staff numbers 1,701 people.
As Islamic insurgents are sweeping down toward Baghdad, we have already begun a partial embassy evacuation, though the State Department prefers to say people are being "temporarily relocated."
Pentagon spokesman John Kirby has assured us that U.S. military forces have the "assets and resources" necessary to evacuate our personnel should Baghdad fall. "But we're not there yet," he said.
A grim President Barack Obama recently told reporters that the situation in Iraq is, well, grim.
Though we have poured billions into training and equipping the Iraqi army, its soldiers have shown the disturbing habit of throwing down their weapons and fleeing the enemy, abandoning cities that U.S. troops once spilled their blood to secure.
Some of those U.S. troops are now fighting in Afghanistan, in a war whose aims we achieved long ago. We went in to disrupt and destroy al-Qaida and remove the Taliban from power so Afghanistan could not be used as a base to launch further attacks against the United States.
That we have accomplished, but nearly 13 years later, we are still there. The cost has been staggering, perhaps as much as $4 trillion, with the White House estimating that it now costs about $1 million per year to deploy a single U.S. service member to Afghanistan.
To end these costs and to draw down most of our forces — some will remain behind to hunt down and kill terrorists — we have spent some $28 billion to create and equip an Afghan army, whose job it will be to prop up the despotic and unpopular regime in Kabul.
We will also continue to spend billions in the belief that Afghanistan can be reshaped into a giant American suburb — say Evanston, Illinois — where people get along, all races and religions have equal rights, women can fully participate in democracy, and the population peacefully avails itself of excellent schools, health care and job opportunities.
"Modern" Afghanistan has not achieved — or even wanted — this for the past three centuries, but the U.S. is determined to throw as many billions into the effort as it takes.
What worries us now, however, is that Iraq was supposed to show Afghanistan the way: Send in U.S. troops; spend a few trillion dollars; supply arms and training to the local armed forces; create a modern, nonsectarian state; and then pull out and watch democracy flourish.
Except it's not happening. Not in Iraq and not in Afghanistan. In fact, it's not even close.
Obama said June 12: "What we've seen over the last couple of days indicates the degree to which Iraq's going to need more help. It's going to need more help from us, and it's going to need more help from the international community."
How much more help?
"I don't rule out anything, because we do have a stake in making sure that these jihadists are not getting a permanent foothold in either Iraq or Syria, for that matter," Obama said.
A week later, a grim Obama strode into the White House briefing room and told reporters: "First, we are working to secure our embassy and personnel operating inside of Iraq. As president, I have no greater priority than the safety of our men and women serving overseas. So I've taken some steps to relocate some of our embassy personnel, and we've sent reinforcements to better secure our facilities."
But don't worry. Our $750 million embassy in Baghdad is the size of 80 football fields.
And if we have to evacuate, it will be much easier to land the helicopters this time.
Roger Simon is Politico's chief political columnist. His new e-book, "Reckoning: Campaign 2012 and the Fight for the Soul of America," can be found on Amazon.com, BN.com and iTunes. To find out more about Roger Simon and read features by other Creators writers and cartoonists, visit the Creators Web page at www.creators.com.