EXCLUSIVE: Bob Woodward to Diane Sawyer: 'This Is Obama's War'

Sept. 27, 2010— -- President Obama grew so frustrated with his own administration's deliberations over the war in Afghanistan that he wound up writing his own strategy, dictating a six-page, single-spaced "terms sheet" that sought to define the military mission and prevent his commanders from further escalating the war, according to a new book by journalist Bob Woodward.

The episode, as recounted by Woodward in "Obama's Wars," came toward the end of a months-long strategy review that resulted in the president's decision to order a surge of 30,000 additional troops late last year -- 10,000 fewer than what top military leaders had been strongly pushing -- with a withdrawal date of July 2011.

The president had all his top aides sign off on the strategy, devised despite the military's push to keep the troop commitment more open-ended. But that didn't put an end to divisions that continue to linger inside the White House, Woodward told ABC's Diane Sawyer in his first interview on the new book.

"He said, 'I want everyone to look me in the eye and tell me they'll go along with this.' And he pushes them," Woodward said in the interview, the first portions of which will air on ABC's "World News" tonight.

"So he gets everyone to go along. But going along is not conviction. And that is part of the dilemma here for Barack Obama. He designed this."

Woodward continued: "If it turns out [that in] July of next year, nine months away, things are much better in Afghanistan, it seems to be working -- he's going to be a geo-strategic genius. If it doesn't work, you've got all kinds of people -- generals, Republicans, Democrats -- who are going to say, 'Wait a minute….'"

"This is Obama's war. He really became the strategist-in-chief."

Watch Diane Sawyer's interview with Bob Woodward tonight on "World News" at 6:30 p.m. ET and more on "Nightline" at 11:35 p.m. ET

The book depicts a president and a White House engaged in an ongoing power struggle with military commanders that started virtually as soon as the president took office, with personal slights and grudges coloring a long series of tense discussions.

And Obama appears sobered by the barrage of threats the nation is facing. In a 75-minute, on-the-record interview in the Oval Office in early July – conducted as Woodward was finishing his book – Obama laid out the threats in unusually stark terms that have already drawn criticism from the right.

"We can absorb a terrorist attack," Obama told Woodward. "We'll do everything we can to prevent it, but even a 9/11, even the biggest attack ever that ever took place on our soil, we absorbed it and we are stronger. This is a strong, powerful country that we live in, and our people are incredibly resilient."