Date: May 26, 2011 Source: Associated Press   Latest developments in Arab world's unrest YEMEN Yemen's embattled President Ali Abdullah Saleh vows not to step down or allow his impoverished nation to become a "failed state" even as urban combat between government troops and armed tribesmen engulf parts of the capital. Both sides raise the specter of civil war as the three-day death toll rises to at least 63. The latest violence comes just days after a failed Arab mediation effort to end the three-month uprising and ease Saleh from power. Saleh's statement rules out a voluntary departure and blasts U.S.-backed efforts to negotiate his exit after 32 years of authoritarian rule. ___ LIBYA Libyan rebels clash with Sudanese mercenaries fighting for Moammar Gadhafi near the border with Sudan, as President Barack Obama predicts the Libyan leader would be forced to step down if NATO keeps up its military campaign with the U.S. playing a key role. Speaking at a news conference in London, Obama says the U.S.-led NATO coalition is engaged in "a slow, steady process in which we're able to wear down the regime forces." Obama said, "I believe that we have built enough momentum that as long as we sustain the course we're on, he will step down." Libyan government spokesman Moussa Ibrahim reacts angrily to Obama's assertion, saying "Gadhafi's destiny, Gadhafi's future, is for the Libyan nation to decide." ___ SYRIA More than 25 children, some of them tortured, are among the victims of the Syrian government's deadly crackdown on an uprising that has killed more than 1,000 people over the past two months, an opposition group says. The Local Coordination Committees in Syria, which helps organize the protests against President Bashar Assad, identifies the children and the circumstances of their death. Syria has blocked media access in the country, making it impossible to verify the reports independently. Some of the children died "under severe torture," the group's statement says noting the children range in age from 5 and 17. ___ BAHRAIN A special Bahrain security court sentences four demonstrators to a year in jail for involvement in anti-government protests, a human rights group says. Wednesday. Three of the protesters were convicted a day earlier on charges that included taking part in illegal protests, according to the Bahrain Youth Society for Human Rights. It says the fourth was found guilty of possessing pamphlets calling for the overthrow of the country's ruling system. The reported convictions are part of a series of closed-door trials in a special court set up in March during a crackdown on the Shiite-led protests.