NEW : Tunisia says it has detained Libya 's former prime minister under Gadhafi . The U.S. has been monitoring Libya 's yellowcake stockpile , a defense official says . Score: 6 Troops have been putting pressure on several regime holdout cities in recent days .
NEW : Tunisia says it has detained Libya 's former prime minister under Gadhafi . The U.S. has been monitoring Libya 's yellowcake stockpile , a defense official says . A military site containing barrels and bags of powder marked `` radioactive '' is revealed . Troops have been putting pressure on several regime holdout cities in recent days .