NATO's secretary-general said this week that the alliance needs more strike aircraft like this Norwegian F-16 fighter, shown taking off from Bodoe, Norway, on March 21, for the operation in Libya. Trond Hoeyvik/Royal Norwegian Air Force/AP hide caption

itoggle caption Trond Hoeyvik/Royal Norwegian Air Force/AP

The last time NPR's Eric Westervelt saw backpacker Billy Six, he was at Benghazi's port trying to catch a boat ride to the besieged city of Misurata. Nasser Nasser/AP hide caption

itoggle caption Nasser Nasser/AP

An injured man with a leg cast in the colors of the Libyan rebel flag sits on the deck of a Turkish ship arriving from Misurata to the port of Benghazi to evacuate the wounded on Sunday. Mahmud Hams/AFP/Getty Images hide caption

itoggle caption Mahmud Hams/AFP/Getty Images

Veteran Libyan soldiers who defected to the rebel side teach volunteers the basics of mortars, machine guns, small rockets and anti-aircraft artillery. Eric Westervelt/NPR hide caption

itoggle caption Eric Westervelt/NPR

Rebels make a quick retreat from Brega as pro-Gadhafi troops fire heavy artillery behind them. Amy Walters/NPR hide caption

itoggle caption Amy Walters/NPR

A Libyan rebel observes at a front-line checkpoint near Zwitina, the outskirts of the city of Ajdabiya, south of Benghazi, eastern Libya, on Thursday. Anja Niedringhaus/AP hide caption

itoggle caption Anja Niedringhaus/AP

Ahmed Jarbou, 45, a businessman from Benghazi, and his 2-year-old daughter, Jude, examine remnants of destroyed mobile artillery from pro-Gadhafi forces. Eric Westervelt/NPR hide caption

itoggle caption Eric Westervelt/NPR