Reports have leaked out over the past week that President Obama will announce that he is sending additional troops into Afghanistan. The only question seems to be whether he will send 30,000, 40,000 or some number in between. That is, frankly, not a very important issue.

And for all of his talk about “off ramps” for the United States if the Afghan government does not meet certain policy targets or “benchmarks,” the reality is that he is escalating our commitment. Since Obama has repeatedly asserted that the war in Afghanistan is a war of necessity, not a war of choice, his talk of off ramps is largely a bluff—and the Afghans probably know it.

There are obvious hazards in equating one historical event with a development in a different setting and time period, but there are a couple of very disturbing similarities between Vietnam and Afghanistan. In both cases, U.S. leaders opted to try to rescue a failing war by sending in more troops. And in both cases, Washington found itself desperately searching for a “credible” leader who could serve as an effective partner in the war effort.

The United States never found such a leader in Vietnam, and was frustrated by a parade of repressive, corrupt, and ineffectual political figures. That experience sounds more than a little like the problem the Bush and Obama administrations have encountered with Afghan President Hamid Karzai and his government. That fact alone suggests that our Afghanistan mission is not likely to turn out well.