For example, he has said that one result of the Iraq war has been to make Iran the most important country in the Middle East, and he worried that Iraq could become an Iranian satellite.

When I interviewed President Obama in the summer of 2010 for my book Obama’s Wars, his deeply rooted aversion to war was evident. As I reported in the book, I handed Obama a copy of a quotation from Rick Atkinson’s World War II history, The Day of Battle, and asked him to read it. Obama stood and read:

“And then there was the saddest lesson, to be learned again and again . . . that war is corrupting, that it corrodes the soul and tarnishes the spirit, that even the excellent and the superior can be defiled, and that no heart would remain unstained.”

“I sympathize with this view,” Obama told me. “See my Nobel Prize acceptance speech.”

I had listened to the speech when he gave it, Dec. 10, 2009, and later read it, but I dug it out again. And there it was:

“The instruments of war do have a role to play in preserving the peace. And yet this truth must coexist with another — that no matter how justified, war promises human tragedy. The soldier’s courage and sacrifice is full of glory, expressing devotion to country, to cause, to comrades in arms. But war itself is never glorious” — Churchill had called it that — “and we must never trumpet it as such. So part of our challenge is reconciling these two seemingly irreconcilable truths — that war is sometimes necessary and war at some level is an expression of human folly.”

That is probably the best definition of the Obama doctrine on war. Applying such a doctrine in today’s dangerous and unpredictable world will be daunting — but on these issues Obama seems to have found a soul mate.

Bob Woodward is an associate editor of The Washington Post. His latest book is ”The Price of Politics.” Evelyn M. Duffy contributed to this column.