US Defence Secretary William Cohen yesterday called on mainland leaders to be creative enough to take advantage of a 'window of opportunity' for resolving tension with Taiwan. But Mr Cohen, after meeting Wang Daohan, the chairman of the mainland's Association for Relations Across the Taiwan Strait, in Shanghai and President Jiang Zemin earlier in Beijing, gave no indication of any breakthrough on the thorny issue of how to reopen the semi-official channel of communication between the two sides. 'In my opinion [Taiwan] President Chen [Shui-bian] has shown some flexibility on this issue and I believe every opportunity should be taken advantage of to explore ways in which reconciliation can be achieved,' he said. 'It is my own belief that there needs to be some creative examination on the part of the Chinese Government to achieve the goal they desire.' While US officials have tried to paint a picture of a modest shifting of the mainland's position on the Taiwan issue, Mr Cohen did not leave that impression with reporters in Shanghai. He said Mr Wang repeated Beijing's position that Taiwan must first make a commitment to the 'one China' principle before long-stalled discussions could be resumed. Earlier Mr Cohen addressed businessmen and mainland officials from the hi-tech trading floor of the Shanghai Stock Exchange. As red and green stock prices flickered on a huge electronic board behind him, the US official told his audience that the mainland's growing ranks of middle-class investors would help seek a greater voice in governing and push for peaceful solutions to national challenges. He also waded into the controversy over Israel's decision - under US pressure - to back out of a US$250 million (HK$1.94 billion) deal to sell advanced airborne radar technology to the mainland. Asked by a stock exchange clerk why Israel could not sell the equipment while the US sold arms to Taiwan, Mr Cohen replied Washington did not want an escalation of weapons purchases. 'If there is the sale by Israel or any other countries that would change that balance of power, then pressure would be generated for Taiwan to acquire something to counter it,' he said.