Protesters hold anti-China placards while marching in an anti-China protest on a street in Hanoi May 11, 2014. Hundreds rallied on Sunday in Vietnam's biggest cities to denounce China's setting up of a giant oil rig in the South China Sea, a rare protest likely to prolong a tense standoff between the two communist neighbours. REUTERS/Kham (VIETNAM - Tags: POLITICS CIVIL UNREST) - RTR3OMK6