VIETNAM has vastly improved its relations with other countries and may soon become a member of the Association of Southeast Asian Nations (ASEAN), according to Belgium's former ambassador to Vietnam, Piet Steel. ''Vietnam has very successfully broken its international isolation and is now friends with almost all countries,'' Mr Steel told the Vietnam Business Association yesterday in his first address as Belgium's Consul-General in Hong Kong. ''Vietnam now has very close relations with ASEAN and the individual member states of ASEAN. They are even now observers to ASEAN. I believe in a very short time Vietnam will become a member.'' Mr Steel, who spent five years in Geneva with the General Agreement on Tariffs and Trade (GATT), believed Vietnam might be able to circumvent what remained of the US trade embargo against it. He said the Vietnamese Government, increasingly impatient with Washington, was abandoning hope for an early resumption of normal relations and was relying less on the US for its economic development. ''Vietnam's re-integration in the world economy is possible without America. Vietnam does not even need normalisation to get access to the big US market. ''If Vietnam proceeded quickly to the GATT, on the understanding that this entry is well negotiated, the country would not have to wait for the conclusion of a bilateral agreement.''