BENGHAZI, Libya — After the uprising, the rebels stumbled as they tried to organize. They did a poor job of defining themselves when Libyans and the outside world tried to figure out what they stood for. And now, as they try to defeat Col. Muammar el-Qaddafi’s armed forces and militias, they will have to rely on allied airstrikes and young men with guns because the army that rebel military leaders bragged about consists of only about 1,000 trained men.

Those frank admissions came from Ali Tarhouni, who was appointed to the cabinet of the rebels’ shadow government on Wednesday as finance minister. Mr. Tarhouni, who teaches economics at the University of Washington, returned to Libya one month ago after more than 35 years in exile to advise the opposition on economic matters. The rebels are proclaiming his American credentials — he has a doctorate from Michigan State University — as they seek foreign recognition of their cause.

“He understands the Western mentality,” said Iman Bugaighis, a spokeswoman for the fledgling opposition government.

But more important, Mr. Tarhouni, 60, who briefed journalists on Wednesday night, appeared to be one of the few rebel officials willing to speak plainly about the movement’s shortcomings and challenges, after weeks of rosy predictions and distortions by some of his colleagues, especially regarding the abilities of the rebel fighters.