Barack Obama has arrived in South Korea on the last leg of his visit to Asia.North Korea’s refusal to engage in nuclear disarmament talks is likely to top the agenda during a planned meeting with South Korean President Lee Myung-bak. However, discussions are more likely to focus on a stalled free trade pact between the two allies. The US president’s tour coincides with a period of heightened tension between Seoul and Pyong Yang coming as it does, just days after warships from both sides exchanged fire on the disputed maritime border. Outside the US embassy, protesters heckled Obama’s entourage. The demonstrators were urging the US to take a tough line with the North Korean dictator Kim Jong Il. A small clash took place as police tried to disperse the crowd but there were no injuries. Earlier a small group of anti-war protesters also demonstrated outside the American embassy. They were protesting against the South Korean government’s plans to re-deploy troops in Afghanistan.