WAH Kwong president Frank Chao has accused the United States of an incoherent shipping policy and of pioneering the ''flag of convenience'' to break away from high crew costs and over-regulation. He told the Marintec China 93 conference in Shanghai that the US, as the world's most powerful nation, should have a ''coherent'' shipping policy. He said the US had special obligations not to react to events unilaterally, both as a matter of policy and to avoid setting a damaging precedent. ''The United States, you might say, is so big and powerful, especially since the demise of the Soviet Union, that it is a law unto itself, that it can do what it wants and that there is little anyone can do about it.'' Being in that position, it was important that it provided a lead to the rest of the world and '' does not commit that worst of all sins in shipping, as well as in trade, namely, legislating unilaterally. ''Yet,'' said Mr Chao, referring to the Oil Pollution Act of 1990 (OPA 90), ''that is what the United States has done so often in the past and continues to do to this day''. Mr Chao said an inward-looking US approach had been characterised by: Cargo preference measures, including the reservation of the coastal trades for US flag vessels. An over-zealous regulatory approach, stemming in part from the deep-seated anti-trust philosophy and a highly developed legalistic approach to anything remotely resembling a dispute. Failure to ratify internationally agreed conventions because of sectoral, national or other concerns. Today, he said, the US deep-sea merchant marine barely existed, although US capital was heavily engaged in shipping under other flags. ''It was, after all, the US which essentially pioneered the 'flag of convenience' - or as they termed it 'flag of necessity' - concept to break away from high crew costs and over regulation,'' Mr Chao said. He said that while no one disputed the environmental aims of OPA 90, many characterised it as ''Uncle Sam having shot himself in the foot''. Because of OPA 90, many owners of all classes of tonnage had opted no longer to trade with the US. He also called upon China, as a growing force in shipping and trading, to abide by the same principles as other countries. He said that in recent months some shipowners trading to China had found themselves in severe difficulties when entering into charters.