I wouldn't put it past him, but if it was him that would certainly compound Newsweak's journalistic and ethical sins, because they described the source as a current "senior Pentagon official".... it would be a huge (though not surprising) ethical lapse to mis-describe the nature of their anonymous source, since they tried to give the claim added credibility by claiming the source was a current "senior Pentagon official"....
Powell could have told them it came from a senior Pentagon official. And maybe it did. I've got some thoughts about efforts made to flush out leakers but that's another day.
Newsweak would have to refer to the source as either a senior pentagon official or the ex-secretary of state just recently. Could be a way to protect Powell's identity.
Someone BIG leaked this to Newsweak.
Unnamed sources again? Shocking.
Unnamed sources lie early and often. If there are people with an inclination to believe and if there is damage to be done, you can be sure that these unnamed sources will be showing up at a MSM affiliate nearest you.