THE United States is doing its modest part to help thaw the cold war that has gripped the Korean Peninsula for 35 years. Travel restrictions between the US and North Korea will be loosened, a trade ban will be eased slightly to allow sale of ``humanitarian goods'' like food and clothing to the North Koreans, and diplomats representing Washington and Pyongyang can again meet in neutral settings. These are cautious steps, directed toward a government that in the past has flagrantly rejected conciliatory overtures and gone on its dogmatic, and sometimes terrorist, way. Tentative diplomatic contacts between the US and North Korea ended in 1987 after evidence pointed to the North's involvement in sabotaging a South Korean airliner.
But the times and temperaments are changing. As the State Department emphasized, the American relaxation of sanctions against North Korea results from initiatives taken by South Korean President Roh Tae Woo.
In a speech at the UN last month, the first by a Korean head of state since the country's partition, Mr. Roh urged progress toward ``a springtime for peace and reconciliation on the Korean Peninsula.'' North Korean Deputy Foreign Minister Yang Sok Ju, also speaking at the UN, repeated familiar themes like removal of all American troops from the South, but also struck an uncharacteristically conciliatory tone.
Roh's desire to mend the rift between North and South reflects his domestic politics. Reunification is an roiling issue in the South, kept heated by activist students who tend to see division as a foreign plot to weaken Korea. Roh was nurtured in the militaristic past, but now appears determined to keep his country on course toward a more democratic future. He has a lot to gain by making the decidedly forward-looking issue of reunification his own. And he professes optimism about the chances of bringing the two Koreas closer together, pointing to warming trade relations between South Korea and the North's biggest backers, China and the Soviet Union.
But the obstacles, clearly, are formidable. South and North Korea are separated by a chasm that's economic as well as political and military. South Korea's gross national product in 1986 was $91 billion; North Korea's estimated GNP for 1984 was $23 billion. The South is pushing toward democracy; the North, under the aging Kim Il Sung, is mired in a repressive, Stalinist brand of communism.
The peninsula's thaw is probably not going to be quick. But every step toward relaxing longstanding tensions in this trouble spot should be welcome. The US shift away from strict isolation of North Korea is another in a recent series of openings. The North Koreans should reciprocate by corresponding steps, such as a renunciation of terrorism.