 U.S. President Barack Obama said on Saturday that developing nations must take "substantial actions" to curb their greenhouse gas emissions and that the world's top emitters must have clear reduction targets. He added in a major speech in Tokyo that there could be no solution to the problems of energy security and climate change without the involvement of the Asia-Pacific region's developing nations, but that these problems could also provide great opportunities. "If we put the right rules and incentives in place, it will unleash the creative power of our best scientists, engineers, and entrepreneurs. It will lead to new jobs, new businesses, and entire new industries," Obama said. About 190 nations will gather in Copenhagen from December 7-18 to work out a global deal to fight climate change after the first phase of the Kyoto Protocol ends in 2012, but talks so far have been clouded by disputes between rich and developing nations. Obama, who has faced resistance from opposition Republicans and even some fellow Democrats to setting caps on U.S. emissions, has previously acknowledged that the U.S. Senate would not pass climate change legislation in time for Copenhagen. "I have no illusions that this will be easy, but the contours of a way forward are clear. All nations must accept their responsibility," he said in his speech. "America knows there is more work to do -- but we are meeting our responsibility, and will continue to do so." The new government in Japan, the world's fifth-biggest emitter of greenhouse gases, has promised to reduce emissions by 25 percent by 2020 from 1990 levels in an effort to strengthen its diplomatic clout at the December meeting. Tokyo is the first stop in Obama's nine-day Asian tour, which also takes him to Singapore for an Asia-Pacific economic summit, to China for talks likely to feature climate change and trade imbalances, and to South Korea, where North Korea's nuclear ambitions will be in focus.