Ethiopia's new leader Hailemariam Desalegn, expected to assume power following the death of the longtime prime minister, readied for the post on Friday after holding talks with US President Barack Obama. But Hailemariam, 47, a relatively little-known politician overshadowed by his mentor Meles Zenawi, who died on Monday, faces tough challenges both internally and across the volatile Horn of Africa region. Obama, who telephoned Hailemariam late Thursday, urged him to "use his leadership to enhance the Ethiopian government's support for development, democracy, human rights and regional security," the White House said. Hailemariam has also met with South Sudan's foreign minister...