Myanmar's junta has given the World Food Program permission to use helicopters to send aid to cyclone survivors, the United Nations said on Tuesday, as flags flew at half-staff across the country to mourn the dead. The first day of a three-day mourning period passed in torrential rain and diplomatic prodding of the reclusive generals to allow more international aid after Cyclone Nargis hit in early May, leaving 134,000 people dead or missing.