The president of Somalia's UN-backed government resigned Monday amid deepening international pressure, a move that could usher in more chaos as a strengthening Islamic insurgency scrambles for power. Within hours of Abdullahi Yusuf's resignation, mortar shells slammed into the pockmarked streets near the presidential palace in the capital, Mogadishu, where the government maintains only a token presence. Yusuf is the latest leader to have failed to pacify Somalia during two decades of turmoil. The Horn of Africa country has been beset by anarchy, violence and an insurgency that has killed thousands of civilians and sent hundreds of thousands fleeing for their lives. "Most of the country is not in our hands," Yusuf said in a speech before parliament in Baidoa - one of the only towns controlled by Somalia's government, which has been sidelined by Islamic insurgents with alleged ties to al-Qaida.