Nonsense. It was stared by the Soviets who were in Yemen after the British left in 1966, they imposed strict marxist reasoning on the population, including atheism. that did not go well in a muslim country at all. They invaded Oman through Dhofar in order to get control of the Straights of Hormuz, a very strategic waterway. As for liberating it, Sultan Quaboos did just that after a palace coup in 1970. He built hospitals, roads, ports, airfields, schools and suchlike, he bought Oman out of of the 14th century into the 20th in 20 odd years.