Of all the experts I have read or consulted lately about the situation in the Middle East, the one who made the most sense was quoted recently in The New York Times. She’s Jennifer Shelton-Armstrong, identified as a 45-year-old Democrat in Mission Viejo, California, who participated in a poll about President Obama’s handling of foreign policy and terrorism. This is what she said: “He is ambivalent, and I think it shows. There is no clear plan.”

Why isn’t she on “Meet the Press”?

Now, other experts will argue that there is a clear plan, that it has been enunciated time and time again by the president, the vice president and various other members of his administration. All this is true, yet the impression the American people have is that Obama has lurched into something of a war as a reaction to the beheadings of two Americans.

The poll in which Ms. Shelton-Armstrong participated was bad news for Obama. The public, by 48 percent to 39 percent, disapproved of “the way Barack Obama is handling the situation with ISIS [Islamic State] militants.” In fact, Obama got poor marks for foreign policy in general. And no doubt the poll would have been even worse had it been conducted after Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, said he might ultimately have to recommend putting boots on the ground: “If we reach the point where I believe our advisers should accompany Iraqi troops on attacks against specific [Islamic State] targets.” In a flash, the White House said, no — never, never, never! But the damage had been done. The administration looked confused.

The problem for Obama — actually, the problem for us all — is that the latest iteration of his foreign policy seemed to come out of nowhere. It lacks what we all now recognize as a back story — a useful Hollywood term. If foreign policy was a movie, critics could fault Obama for a script that does not prepare the audience for a stark change of character. He was above all a president who only wanted out of Iraq. He fairly fled the place. His policy was to uninstall, as the techies might say. Even his Cairo speech of 2009 promised “a new beginning between the United States and Muslims around the world.” Out with the old. In with the new. Reboot.

We all could appreciate the sheer horror of the decapitations and the threat posed by the Islamic State — to the region but not, really, to the United States. I think Obama is on the right course now — just as he was right to thwart what seemed like an imminent genocide, the vowed extermination of the Yazidis in northern Iraq. If you can save 10,000 lives with an air campaign without really risking any of your own, why not do it? (The U.S. lost no lives in the Libyan or Bosnian air campaigns.)

I also favored an early intervention in the Syrian civil war back when there were moderates and a little assistance could have gone a long way. Obama ruled that out. More than 200,000 people have been killed and millions made refugees. Maybe this would have happened anyway, but there was no real harm in trying — in doing, really, what is being done now ... pathetically late.

I recently watched the marvelous PBS series “The Roosevelts” — TR, FDR and the equally astonishing Eleanor. What comes through is the persistent and methodical way Franklin Roosevelt prepared the nation for war. He could see it coming; he had a worldview; he had a policy and he had a course of action. Any documentarian looking for something similar with Obama would go mad.

The campaign — I shall not say “war” — that Obama vows against the Islamic State will be difficult but not impossible. The enemy can hide in towns and cities and take cover in the vegetation along the banks of the Tigris, Euphrates and Diyala rivers. And victory, if it comes, will present its own problems. Newly robust Shiite, Kurdish and other militias, lacking a common enemy, may turn on each other. As much as oil, the region is rich in enmities.

Things may yet get worse — and even more complicated. (Are there any more ethnic groups yet to be heard from?) In that event, Obama has to ready the American people for whatever may come. Yet, he operates in spurts — a speech here, a speech there and then a round of golf. What he needs — what we need — is consistency of message and, above all, a willingness to re-examine his own assumptions. Ms. Shelton-Armstrong, among others, deserves clarity.

Richard Cohen is a writer with the Washington Post Writers Group. He can be reached at cohenr@washpost.com.