SOUTH KOREA TO KEEP TRADE SURPLUS 3-5 YEARS South Korean Trade Minister Rha Woong Bae said his nation would maintain a trading surplus for three to five years as a way to cut its foreign debt. He said in an interview with Reuter that after a few years it was likely South Korea would drop barriers to foreign goods and move toward a more balanced trade position. He said the present trade surplus was vital if his nation was to reduce its 44.5 billion dlr foreign debt. Rha said that 1986 was the first year South Korea had a trade surplus - 4.5 billion dlrs, against a 1985 deficit of 900 mln dlrs. Rha made his remarks at the end of a two-week trade mission here during which a team he led agreed to buy U.S. products valued at 1.8 billion dlrs. About 800 mln dlrs of the purchases here were in goods of the type South Korea normally bought from Japan. Rha leaves today for Ottawa for trade talks with Canadian officials and businessmen. Asked if South Korea would retaliate against U.S. goods if Congress closed U.S. markets to its products, he said "at this moment, we have no thought of retaliation." South Korea is a major exporter to the U.S. of textiles and apparel and electronic goods, such as television sets, video cassette records and personal computers. Its purchases from the United States include electronic testing equipment, grains and cotton.