SYDNEY (Reuters) - An Asia-Pacific climate change agreement was a milestone because it marked the first time the world's biggest polluters had pledged to cut greenhouse gas emissions, Australia's Prime Minister said on Sunday. "This is the first such agreement involving the major polluters -- the United States, China and the Russian Federation," John Howard told a news conference following the Asia Pacific Economic Cooperation summit. "And (it) is therefore a very important component, along the hard march of mankind towards reaching a sensible, workable, international agreement to cover the period post-Kyoto, that is 2012 onwards," he said. Pacific Rim...