When President Obama meets with China's President Hu Jintao at the G-20 summit on Thursday, Obama is likely to mention human rights, and perhaps even bring up the case of imprisoned dissident Liu Xiaobo, who was awarded the Nobel Peace Prize last month. For some insight into how President Obama might broach the topic, NPR's Melissa Block talks with Kenneth Lieberthal, director of the China Center at the Brookings Institution, and former senior director for Asian Affairs at the National Security Council under President Clinton.