BRUSSELS – NATO acknowledged Friday that its airstrikes had hit rebels using tanks to fight government forces in eastern Libya, saying no one told them the rebels used tanks. British Rear Adm. Russell Harding, the deputy commander of the NATO operation, said in the past, only forces loyal to Libyan strongman Moammar Gadhafi had used heavy armored vehicles. Harding says the rebels and government troops are engaged in a series of advances and retreats between the eastern coastal towns of Brega and Ajdabiya, making it difficult for pilots to distinguish between them.