South Korea's president urged North Korea on Sunday to quickly return to stalled disarmament talks, saying engagement with the international community will serve its national interests better than missiles and nuclear weapons. Tension between the two Koreas has run high since conservative, pro-US President Lee Myung-bak took office in Seoul one year ago. It has further intensified in recent weeks amid reports the North plans to test-fire a long-range missile. Pyongyang cut off ties with Seoul and halted joint projects in protest of Lee's hardline approach, which includes suspension of his liberal predecessors' policy of sending unconditional aid to the North. "What protects North Korea is not nuclear weapons and missiles but South-North cooperation and cooperation with the international community," Lee said in a nationally televised speech. "No one should tarnish stability and peace on the Korean Peninsula. That will never succeed."