YEMEN
Thousands of armed tribesmen clash with government troops in the mountains, preparing to march into Yemen's capital to reinforce their brethren. Artillery and gunbattles in Sanaa force closure of Yemen's main international airport. To the south, tribesmen attack government forces in a second city, Taiz, highlighting how the Sanaa fighting threatens to flare around the highly fragmented nation, home to an active al-Qaida branch. Nearly four months of mostly peaceful street protests calling for democratic reforms and the end of President Ali Abdullah Saleh's 33-year rule have given way to an eruption of violence between Saleh's security forces and fighters loyal to Sheik Sadeq al-Ahmar, head of the country's most powerful tribal confederation.
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LIBYA
NATO blasts Tripoli with a series of air strike, sending shuddering booms through the city. Ambulances, sirens blaring, could be heard racing through the Libyan capital after the rattling blasts. A NATO statement says the attacks hit military vehicle and ammunition depots, a surface-to-air missile launcher and a fire control radar system. The air strikes rain down hours after NATO and its partners say they will extend the Libyan mission for 90 more days in support of the rebels fighting the regime of ruler Moammar Gadhafi.
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SYRIA
Syrian troops pound a central town with artillery and gunfire, renewing attacks in a restive area that has been largely cut off from outside contact for six days. At least 15 people are killed, bringing the total killed there to 72 since the onslaught began. What started as street demonstrations calling for reforms evolves into demands for President Bashar Assad's ouster in the face of the violent crackdown, especially in Syria's south and center, where the challenge to his family's 40-year-rule is seen as strongest. Activists say more than 1,100 people have died in the crackdown and 10,000 have been detained, but it hasn't slowed the protests, which take place nearly daily and swell into the thousands each Friday.
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TUNISIA
At least 200 immigrants are missing and two are dead after a fishing boat carrying hundreds of immigrants sinks off the coast of Tunisia in a storm. The boat is believed to have set sail from Libya and was en route to Italy with an estimated 800 would-be immigrants from sub-Saharan Africa and Asia on board, including women and children.