Seoul , South Korea ( CNN ) -- President Obama wrapped up an eight-day tour of Asia on Thursday , holding talks with South Korean President Lee Myung-bak and speaking to American troops at Osan Air Base . Nuclear negotiations involving North Korea and Iran highlighted a news conference held by the leaders . Obama announced that he will send American envoy Stephen Bosworth to North Korea on December 8 for bilateral talks on dismantling Pyongyang 's nuclear program . `` If North Korea is prepared to take concrete and irreversible steps to fulfill its obligations and eliminate its nuclear weapons program , the United States will support economic assistance and help promote its full integration into the community of nations , '' Obama said . `` That opportunity and respect will not come with threats . North Korea must live up to its obligations . '' Obama also said the United States and its allies were working on steps to take against Iran after its apparent rejection of a nuclear deal . `` We have begun discussions with international partners about the importance of having consequences , '' Obama said . `` Our expectation is that , over the next several weeks , we will be developing a package of potential steps we could take that will indicate our seriousness to Iran . I continue to hold out the prospect that they may decide to walk through this door . I hope they do . '' Iran rejected a key plank of a deal Wednesday designed to ease international fears that Tehran aims to build nuclear weapons . Iranian Foreign Minister Manouchehr Mottaki said his country will not send its partly enriched uranium abroad to be turned into material for medical research , but added that Tehran might allow its nuclear material to be reprocessed inside Iran , the semiofficial ISNA news agency reported . The deal hammered out in November with the help of the U.N. watchdog agency aimed to reduce the amount of raw material Iran has to build a nuclear bomb . Tehran denies that it wants to do so , saying its nuclear program is to produce civilian nuclear energy and do medical work . During their news conference , Obama and Lee also expressed support for a stalled U.S.-South Korea free trade agreement . The deal was signed in 2007 , but has yet to be ratified by the legislatures of either country . South Korea was the final stop on Obama 's four-nation tour of Asia . Obama began his trip in Japan before traveling to Singapore , where he attended the Asia-Pacific Economic Cooperation summit and the Association of Southeast Asian Nations economic forum , meeting on the sidelines with world leaders including Russian President Dmitry Medvedev . Obama then traveled to China , where he met with leaders including President Hu Jintao . After their talks , the two spoke of a common vision of shared responsibilities and economic opportunities . Trade , nuclear proliferation , climate change and the sticky issue of human rights were part of their discussions . Obama , whose flight will stop for refueling in Alaska , is due back in the United States on Thursday .
President Obama returning to United States after four-nation tour of Asia . Obama announced plans to send envoy to North Korea for nuclear talks . Obama met with South Korean President Lee Myung-bak to discuss free trade agreement .