KABUL, Afghanistan – Michael Hastings, the author of the Rolling Stone McChrystal profile, is currently in Afghanistan on an embed with the U.S. military. During a phone interview he said he's just beginning to learn about the impact his article is having.

Hastings said he basically stumbled onto unprecedented access with McChrystal.

After McChrystal's press advisors accepted a request for a profile in Rolling Stone, Hastings joined McChrystal and his team in Paris. It was supposed to be a two-day visit, followed up by more reporting time in Afghanistan.

The volcano in Iceland, however, changed the plans. As the ash disrupted air travel, Hastings ended up being "stuck" with McChrystal and his team for 10 days in Paris and Berlin.

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Due to the volcano, McChrystal had to travel from Paris to Berlin by bus. Hastings said McChrystal and his aides were drinking on the road trip "the whole way."

"They let loose," he said. "I don't blame them; they have a hard job."

Hastings then traveled with McChrystal in Afghanistan for more reporting. In the end, what was originally supposed to be a two-day visit, turned into a month, in part thanks to the disruptions created by the volcano.

Hastings said McChrystal was very "candid" with him and knew their conversations were for reporting purposes. "Most of the time I had a tape recorder in his face or a notebook in my hand," he said.

Hastings said most of the critical comments, which are now causing a stir, were said in the first 24 hours or so of his reporting.

"It wasn't a case of charming him into anything," said Hastings.

He added that there hasn't been any push back or denials from McChrystal because has most of the quotes on tape.

Hastings has done a few trips to Afghanistan before, but is better known for his reporting in Iraq.

He wrote an emotional book "I Lost My Love in Baghdad: A Modern War Story," that describes his experiences in Iraq and the tragic death of his girlfriend who moved to Baghdad to be with him.

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