Washington — One of the less-happy legacies of US military involvement in the Far East is moving closer to resolution.
This is the plight of tens of thousands of Amerasians, the ''warriors' children'' left behind by American servicemen, many to face continued deprivation and discrimination because of their mixed race.
Under proposed legislation rapidly gaining support, such children would be given preferential treatment as immigrants to this country. Among the battalion of more than 160 senators and representatives sponsoring the bill is a cross section of Republicans and Democrats, including prominent conservatives and friends of President Reagan.
Proponents point out that the new law would not increase the number of immigrants, nor would it involve any public cost since each child would have to have a private sponsor. Proof that the father was a US serviceman would have to be shown before a child could obtain a US visa.
Estimates of the number of Amerasian children vary widely. The Rev. Alfred Keane, director of the St. Vincent's Home for Amerasians in Seoul, Korea, puts the total at more than 35,000, including 2,000 in Korea, 1,500 in Japan, 1,000 in Taiwan, 5,000 in Thailand, 1,000 in Laos, and 25,000 in Vietnam and the Philippines. Other estimates range to 80,000 or more.
But more generally agreed upon are the conditions under which many (perhaps most) of these children live. Many are orphans or ''street children,'' but even those who live with their mothers often suffer.
''When the father is absent, which is almost always the case with Amerasians, the key to life in Asia and all its aspects of socialization and acculturation as well as general societal acceptance is missing,'' says John A. Shade, executive director of the Pearl S. Buck Foundation. ''The father is key to birth registration, legitimacy, citizenship, education, employment, and marriage. . . .''
In congressional testimony, Fr. Keane described the ridicule and abuse of ''those forgotten American children of Asia.''
Under current immigration law, such children are in the sixth and last preference category (skilled and unskilled workers in short supply) for receiving visas. This means they rarely are accepted, and if so must wait at least 5 to 10 years.
Under the bill written by Rep. Stewart B. McKinney (R) of Connecticut, they could move up to the first preference category (unmarried children of US citizens). To do this they would have to prove to the appropriate US consular officer that they were born after 1950, and that their fathers were US servicemen. They also would need a guarantee of financial support for at least five years.
A companion bill in the Senate is sponsored by Jeremiah Denton (R) of Alabama , who was a prisoner of war in Vietnam for many years. One of the co-sponsors is Paul Laxalt (R) of Nevada, President Reagan's closest personal friend on Capitol Hill.
To those (including some in the administration) who worry about possible illegal aliens, Senator Denton says: ''The proof of paternity and sponsorship standards are sufficiently rigid to discourage fraud.''
Senator Denton and others point out that European nations that had military personnel in Asia in the past welcomed the children of servicemen to their countries.
''Other great nations which have been active in Southeast Asia, such as France, took these children back with them when they returned home, gave them citizenship and supported them until they completed their education,'' says Fr. Keane.
Similar legislation has foundered in the past. But with the large and diverse sponsorship on Capitol Hill, as well as the growing appreciation for Vietnam veterans, supporters say they are ''very optimistic.''