U.S. Defense Secretary Robert Gates was clueless when he met U2 rock star Bono - as he had no idea who he was. The "With Or Without You" star met the politician at the Pentagon in Washington D.C. on Thursday as part of his efforts to persuade world leaders to increase aid to developing nations.

The U2 frontman and humanitarian has already pressed French president Nicolas Sarkozy to stick to plans to raise development assistance to poorer countries, particularly those in Africa, and he continued his campaign with a low-key meeting with Gates.

But the 64-year-old admits he was impressed by Bono's knowledge of world affairs but had no clue about his rock star status.

He says, "It's a matter of age. I thought U2 was an airplane. (But) my daughter nearly had an aneurysm when I told her who I was meeting with."

(This news article provided by World Entertainment News Network)