IN its war with Vietnam, the United States used to call its failed psychological war 'winning hearts and minds'. Southern village children were taught baseball by US Marines and given candy and plastic tooth-brushes - the vanguard of American culture to keep them from falling for the lure of communism. Now as US Secretary of State Warren Christopher flies home to Washington after becoming at the weekend the most senior American official ever to visit Hanoi he has ensured shades of the policy remain. He told a group of Hanoi international relations students the future was in their hands. 'The key to success in this rapidly changing world is the freedom to own, to buy and to sell; the freedom to participate in the decisions that affect our lives,' he said. 'Each of you ought to have the right to help shape your country's destiny, as well as your own.' With these words in Hanoi, Mr Christopher has signalled a new relationship with his former enemy that will be far different than between Hanoi and any other state. It was his longest speech, but large parts of it have yet to surface in the Vietnamese press. No other leader had been so brazen in calling - on Vietnamese soil - for change from Hanoi's Communist Party leadership. Mr Christopher claimed the hunt for the remains of 1,615 missing American servicemen was the priority in future ties, but spent the bulk of the speech calling for faster change to a free and open society. Twenty years after the end of the war, he has presented Washington as an agent of change. Vietnam has recently been treated lightly over human rights by the State Department and Amnesty International in comparison with other Asian countries such as Burma and China, but Mr Christopher wants more. The country is still under one party rule with its economy still managed and all property ultimately in the hands of the state. 'We will carry out [reforms] at the highest speed we can in conformity with the specific conditions of Vietnamese society,' Foreign Minister Nguyen Manh Cam said yesterday. 'All the liberties and all the freedoms of individuals are clearly guaranteed in our constitution and in reality all these rights are observed. Mr Christopher, however, pegged all future dealings to the chance of change. 'This is a time of great possibility for our relations with Vietnam, for your country's continued growth and its integration in the region. But while further progress is possible, it is not guaranteed.' Hanoi is now waiting for official reaction, with many diplomats believing there will be little public comment. 'This has shocked us all that the US would take this line so soon,' one government official and party member said yesterday. 'The more things change, the more they stay the same . . . the US has made its agenda very clear. We always knew they would not come back on their knees.' The state press reported the speech only in as far as it praised Hanoi's reforms to date.