Fighting escalated Wednesday in Sudan's capital, Khartoum, as talks between the rival groups continue in Saudi Arabia. U.S. negotiators are "cautiously optimistic" about a possible short-term cease-fire to allow humanitarian aid into the country, Under Secretary of State Victoria Nuland told the Senate Foreign Relations Committee Wednesday. BBC News correspondent Barbara Plett Usher joined Anne-Marie Green on "CBS News Mornings" to discuss the latest developments.
