ON A Bekaa Valley playing field gilded by late-afternoon sun, hundreds of young men wearing Boy Scout-style uniforms and kerchiefs stand rigidly at attention as a military band plays, its marchers bearing aloft the distinctive yellow banner of Hezbollah, the militant Shi'ite movement. They are adolescents – 17 or 18 years old – but they have the stern faces of adult men, lightly bearded, some of them with dark spots in the centre of their foreheads from bowing down in prayer. Each of them wears a tiny picture of Ayatollah Ruhollah Khomeini, the Shi'ite cleric who led the Iranian revolution,...