Jan 8 (Reuters) - Somalia's President Abdullahi Yusuf entered Mogadishu on Monday for the first time since taking office in late 2004, a government source said. Islamists fled the Somali capital they had controlled for six months in the face of advancing Ethiopian and government troops before the New Year. Here are key facts about Yusuf: * Born in December 1934, Yusuf was a career soldier and served as Somalia's military attache to the former Soviet Union in the 1960s. He was jailed for six years for refusing to take part in the 1969 coup that put Mohammed Siad Barre in power. He defected to Kenya after taking part in a failed 1978 coup against Barre. * Ethiopia's military regime detained him from 1985 until May 1991 after he opposed their attempts to seize disputed territory along the Somalia-Ethiopia border. His imprisonment also involved a falling-out with Ethiopian strongman Mengistu Haile Mariam, who was said to have paid Yusuf at least $1 million to help destabilise Barre's regime. * He led Somalia's autonomous enclave of Puntland from 1998-2004. The strategic territory was mostly peaceful under Yusuf's rule except from mid-2001 to mid-2002, when he was deposed over widespread objections to his attempt to lengthen his term of office. Yusuf is disliked by the leaders of neighbouring Somaliland because of sporadic clashes the two sides have fought over disputed border territory. * In 2000, Yusuf opposed Somalia's attempt to restore order when an Arab-backed Transitional National Government was created at a conference of elders. Due to opposition from the country's many warlords, including Yusuf, the TNG's authority withered within months. In October 2004, in the 14th attempt since 1991 to restore central government, lawmakers elected the Ethiopian-backed warlord Yusuf as president. Participants say Ethiopia, Kenya and Yemen backed his election with cash. * Diplomats say Yusuf has struggled to rid himself of his soldier's mindset when dealing with political problems, but his backers say he has been even-handed. His forceful nature, they say, is just what is needed to tame Somalia. In September 2006, Yusuf escaped the country's first suicide bomb attack, which killed five people in Baidoa. He blamed it on al Qaeda and Islamists.
