WASHINGTON (Reuters) - Chinese President Hu Jintao called on Sunday for an end to zero sum Cold War behaviour and suggested new cooperation with the United States in areas like energy, infrastructure development, aviation and space. Hu, who will visit Washington this week, struck an overall upbeat tone about ties with the United States in a very rare written interview with two US newspapers, the Wall Street Journal and the Washington Post. We should abandon the zero-sum Cold War mentality, he declared, and respect each others choice of development path. Hu said he sees signs of relaxation in tensions between North and South Korea, an issue of major concern to both Washington and Beijing. Thanks to joint efforts by China and other parties, there have been signs of relaxation, Hu said. He added that he was convinced an appropriate solution to the Korean nuclear issue could be found, a reference to North Koreas nuclear arms programs. Speaking of the international currency system, which is dominated by the US dollar, Hu called it a product of the past but said it would be a fairly long process to make Chinas own currency an international one. He also said the liquidity of the US dollar should be kept at a reasonable and stable level.