It doesn’t have “terrorist” groups. But the world’s youngest nation isn’t safe. Washington was instrumental in helping sub-Saharan South Sudan become independent from Arab-dominated Sudan, but the government of ethnic Dinka President Salva Kiir has seemingly turned against it. This week State Department officials testified before a congressional subcommittee that Kiir’s troops ambushed a U.S. Embassy convoy and brutalized American aid workers. “This is not accidental,” says one former U.S. official, who believes Kiir wants to drive out foreigners so he can conduct the civil war against ethnic Nuer rivals without restraint.