Blockade succeeds where sanctions failed as Iran oil exports stall

By Ahmad Ghaddar, Enes Tunagur and Robert Harvey LONDON, Sept 1 (Reuters) - For the first time on record, Iran has gone about seven weeks without shipping meaningful crude exports through the Strait of Hormuz, as a U.S. naval blockade succeeds where years of sanctions failed by cutting off one of Tehran's main sources of foreign-currency earnings.