 Smith was confident that the British military would never agree to engage in what he said would be a " fratricidal war " against Rhodesia ; he was proven correct when a British Ministry of Defence council , convened by Wilson and headed by Denis Healey , determined such intervention " impossible " , citing various logistical problems , the danger of provoking a pre @-@ emptive Rhodesian attack on Zambia , and the psychological issues that would surely accompany any confrontation between British and Rhodesian troops . Wilson therefore put all his eggs in the sanctions basket , predicting in January 1966 that the embargo would bring Rhodesia to its knees " within a matter of weeks rather than months " . The UN embargo proved ineffective , largely because both Portugal and South Africa refused to participate . Both declared themselves neutral in the Rhodesian affair , and continued to supply Rhodesia with vital resources such as oil , both at a governmental level and privately . Portugal provided the seaports of Mozambique and the oil refinery at Lourenço Marques . Car stickers marked " obrigado moçambique " — " Thank You Mozambique " — quickly became popular with white Rhodesian motorists . 
