MOGADISHU, SOMALIA - Somali militants linked to al-Qaeda briefly asserted control over Mogadishu's most strategic road Saturday, escalating their efforts to overthrow the U.S.-backed transitional government in a region where Islamic radicalism is gaining strength. Never have the radical al-Shabab militiamen attacked so near Somalia's halls of power as they have last week, bringing them closer to their desire to create a Taliban-like Islamic emirate from which to export jihad abroad.