U.S. President Barack Obama left Seoul, where he met with his South Korean counterpart Lee Myung-bak today, wrapping up his four-nation Asia trip. Earlier in the day, Obama met with Lee on ways to strengthen their alliance, to denuclearize the Korean Peninsula, and to move forward on the bilateral free trade pact.At the joint press conference held with Lee, Obama also announced that Stephen Bosworth, special U.S. representative for the North Korea policy, will visit Pyongyang on the 8th of next month in a bid to prod the nation back to the six-party talks. The Lee-Obama meeting is the third of its kind since Obama's swearing-in in February.