Article Photos: Obama's return a test of evolving foreign policy 4/4

  FILE - In this Tuesday, Sept. 18, 2012 file photo, Chinese military troops march before U.S. Defense Secretary Leon Panetta arrives at the Bayi Building in Beijing, China. The phrases to describe some of the looming foreign policy challenges for U.S. President Barack Obama didn't even exist when he took the oath of office the first time: the Arab Spring, the Fordo Facility housing Iran's underground uranium enrichment labs, the stealth power of new viruses bearing names such as Stuxnet and Flame in the shadow world of cyber-sabotage. Obama's re-election averts the immediate prospect of the United States designating China a currency manipulator, which Romney had promised to do on his first day in office. That would have been a setback to relations and could even have triggered a trade war between the world's two biggest economies.(AP Photo/Larry Downing, Pool, File)