What complaint against the United States do Iraq and North Korea have in common? Both thought they had a green light from American officials prior to invading their neighbors, and both were surprised by the American military response.

The North Korean case is well established. In January of 1950 Secretary of State Dean Acheson gave a public speech in which he drew America's defensive perimeter in the Western Pacific. He left out South Korea, and five months later North Korean tanks rolled over the border.

Now it appears that Saddam Hussein thought Kuwait was fair game on the strength of a conversation he had with Ambassador April Glaspie. A week before the invasion, as Iraqi forces gathered on the Kuwaiti border, Ambassador Glaspie told Saddam Hussein that "we have no opinion on Arab-Arab conflicts, like your border disagreement with Kuwait." She added that the secretary of state had directed her to emphasize this. Still more could be said on the basis of the partial transcript that appeared in The Post of Sept. 13, but perhaps we should wait until the whole document becomes available.

The United States makes a habit of getting into wars unnecessarily. We ought to pay more attention to the mechanics of how this comes about, in the hope that we might learn from experience. One useful law for our diplomats: Never tell a dictator that he can launch a war with impunity. Some 55,000 Americans died in the Korean War, and the entire peninsula was devastated.

E. G. WINDCHY Alexandria

I guess Jim Hoagland's op-ed piece of Sept. 17 {"The Tale of a Transcript"} is to be commended for making the public aware of the naivete of the U.S. diplomatic response to Saddam Hussein's inquiry as to what would happen if he decided to punish Kuwait for its failure to toe the line on oil-level production and its alleged stealing of Iraqi oil. With more than 300 tanks plus armored troop carriers standing at the ready only five miles from the Kuwaiti border, Saddam Hussein still wanted clear assurance that the United States would stay out of the conflict if he moved on Kuwait. Did we give him such assurance? Only in spades! Our pathetic ambassador, April Glaspie, buttressed by Jim Baker's top public affairs aide, Margaret Tutwiler, and his chief assistant for the Middle East, John Kelly, publicly confirmed to Saddam Hussein that the United States was not obligated to come to Kuwait's aid if the emirate were attacked.

These are the most disastrous disavowals of U.S. responsibility toward a threatened friendly nation since Dean Acheson's public declaration in 1950 that South Korea lay beyond the U.S. defense perimeter in Asia.

Only our immediate protests and action stopped Saddam Hussein at the Kuwaiti border. But certainly this must have shocked him as he thought these able U.S. diplomats in Baghdad and Washington had assured him there was no such plan. As a result we have some 150,000 U.S. and other forces in the Saudi desert and offshore with no way knowing of when we will ever get them out. Had we maintained a staunch position against Saddam Hussein we could at least have had time to bring the United Nations to move against this ominous threat. We could also have saved more than $25 billion and the misery of our poor troops. LESTER J. HOOK McLean

Jim Hoagland's "The Tale of a Transcript" is both fascinating and alarming. If it is, as I assume, accurate and if Ambassador Glaspie is a Foreign Service professional, there are only two plausible explanations for such an egregious gaffe. The first, total incompetence at several levels of the National Security Council, White House and Department of State, is hardly credible -- especially in an administration that prides itself on its strong foreign policy orientation. The second, that Saddam Hussein's threats were ignored in the cynical expectation that he would create a crisis that would overshadow our domestic problems, is -- if anything -- even more incredible since history is loaded with disastrous examples of the consequences.

Virtually any other explanation would be preferable, and I hope that someone can suggest one. But while we're committed to the current course and must support the administration's pursuit of it, Congress should also conduct an investigation of all the preceding events.

GERARD V. D'AMORE Rockville