US President Barack Obama arrived in South Korea Wednesday for talks that will focus on how to tempt North Korea back to nuclear disarmament talks and a delayed trade pact between Seoul and Washington. North Korea stoked regional tension ahead of Obama's first tour of Asia since taking office by this month, sparking a naval firefight with the South and declaring it had produced a fresh batch of arms-grade plutonium. South Korean officials said North Korea would top the agenda when Obama meets President Lee Myung-bak Thursday. Also to be discussed is a trade deal bogged down by US objections that it does not do enough to open the South Korean market to US products, including cars. “They will be strongly pressing for North Korea to give up its nuclear weapons, but simultaneously letting the state know it has much to gain if it does,” said Chung Seong-chang, an analyst at the Sejong Institute think tank near Seoul. The Obama administration plans to send its first envoy to North Korea in the next few weeks to revive comatose six-way talks on ending the North's nuclear ambitions in return for massive aid to repair its failed economy and better global standing for the largely ostracized state.