UNITED NATIONS (AP) _ I have come here today to represent the United States, at the request of President Reagan, because of the importance of the issues at stake - not just the terrible human tragedy of Iran Air 655, but the continuing conflict between Iran and Iraq and its implications for international commerce in the Persian Gulf.

Having been my country's permanent representative to this body, I know what a grave responsibility the council bears and the good it can do when it acts with realism and wisdom. We are in urgent need of realism and wisdom now.

Mr. President, the Persian Gulf is a region of vital importance to the United States and the economy of the world. American and European forces are in the gulf, with the support of the states of the area, to meet a vital need - to help ensure the unimpeded flow of oil and to keep neutral commerce moving in the face of a very real threat to innocent shipping. This is our legal right.

Iranian mines, deliberately sown, have disrupted innocent passage and damaged unarmed merchant vessals and a U.S. Naval ship in international waters. Iranian smallboat attacks on non-belligerent merchant ships continue unabated. These actions are in blatant violation of international law. They give the lie to Iran's assertions that it supports freedom of navigation in the gulf.

We have increased the size of our forces from traditional levels to protect U.S.-flag shipping and to assist other neutral vessels under unlawful attack, when they request assistance. Five European navies in addition to our own - a total of some 43 ships - are now in the gulf to counter Iran's reckless behavior toward neutral ships engaged in lawful commerce. I am proud of our leadership in meeting this challenge.

Together we have made it clear that we will keep the Persian Gulf open, no matter what the threat. I am here to reaffirm to those who depend on us and to those who would threaten us, that we will not alter this course. Mr. President, the critical issue confronting this body is not the how and why of Iran Air 655. It is the continuing refusal of the government of the Islamic Republic of Iran to comply with Resolution 598, to negotiate an end to the war with Iraq, and to cease its acts of aggression against neutral shipping in the Persian Gulf.

The victims of Iran Air 655 are only the most recent casualties of a brutal and senseless war that has brought immense pain and suffering to the people of both sides.

Iran long ago could have accepted, and can still accept, an honorable end to the war. As a first step, it should declare its readiness unequivocally to comply with Resolution 598 - today, for the first time, before this body. It can act now to end the unspeakable sacrifices the people of both Iran and Iraq are being asked to make. What possible objectives could be worth the human suffering and pain, the hundreds of thousands of casualties, and the economic devastation the war has caused on both sides?

A particularly horrifying aspect of the Iran-Iraq war is the increasingly routine use of chemical weapons. Who can forget the pictures of entire families lying dead in the streets of their villages, innocent of anything, yet killed in this savage way?

The United States was the first nation publicly to condemn the use of chemical weapons in the war as a blatant violation of the Geneva protocols. We fully support Security Council Resolution 612, which demands an immediate end to chemical warfare by both parties. No country should think it can use chemical weapons with impunity.

We respect Iran's right to air its grievances. But Iran cannot have it both ways. Iran cannot simultaneously complain to this body and defy it.

The government of the Islamic Republic of Iran has refused to say plainly and clearly that it will comply with the mandatory decision of the Security Council. Iran must not be permitted to choose those provisions of Resolution 598 it likes and ignore the others. Nor can Iraq be permitted to rest on verbal adherence to Resolution 598, while avoiding cooperation with the secretary-general in finding practical ways to implement the resolution.

As for the immediate matter at hand - the unfortunate destruction of Iran Air 655 - many of the circumstances remain unclear. Our own military investigation is under way. We will also cooperate with any investigation that is conducted by the International Civil Aviation Organization, and we trust that the government of Iran will do the same. We want all the relevant facts to be brought to light as quickly as possible.

But one thing is clear: The U.S.S. Vincennes acted in self-defense.

This tragic accident occurred against a backdrop of repeated, unjustified, unprovoked, and unlawful Iranian attacks against U.S. merchant shipping and armed forces, beginning with the mine attack on the USS Bridgeton in July 1987. It occurred in the midst of a naval attack initiated by Iranian vessels against a neutral vessel and, subsequently, against the Vincennes when it came to the aid of the innocent ship in distress.

Despite these hostilities, Iranian authorities failed to divert Iran Air 655 from the area. They allowed a civilian aircraft loaded with passengers to proeed on a path over a warship engaged in battle. That was irresponsible and a tragic error.

The information available to Captain Will Rogers, the captain of the Vincennes, indicated that an Iranian military aircraft was approaching his ship with hostile intentions. After seven unanswered warnings, he did what he had to do to protect his ship and the lives of his crew. As a military commander, his first duty and responsibility is to protect his men and his ship.

The United States has never willfully acted to endanger innocent civilians, nor will it ever. But I can also assure you that the United States will never put its military in a dangerous situation and deny them the right to defend themselves.

Mr. President, we are all accustomed by now to hearing irresponsible charges from the Iranian government. There have been many particularly egregious statements concerning this tragic incident.

I will not dignify with a response the charge that we deliberately destroyed Iran Air 655. The Foreign Minister of Iran knows better. He knows that this tragedy was an accident. He also knows that by allowing a civilian airliner to fly into the area of an engagement between Iranian warships and U.S. forces in the gulf, Iran must bear a substantial measure of responsibility for what has happened.

I call on Iran today to reroute civilian air traffic away from areas of active hostilities. Yesterday, the U.S. representative to the International Civil Aviation Organization advocated an investigation by the ICAO into the Iran Air incident and immediate consideration of appropriate measures to ensure the safety of civil aviation in the gulf.

Mr. President, the terrible disaster of Iran Air 655 fills our hearts with sorrow. Our reaction to this tragedy transcends political differences and boundaries. As Americans, we share the grief of the families of the victims, whatever their nationalities.

It is that strongly felt sense of common humanity that has led our government to decide that the United States will provide voluntary, ex gratia compensation to the families of those who died in the crash of Iran Air 655.

We make this offer as a humanitarian gesture - not as a matter of legal obligation but out of a sense of moral compassion, reflecting the value we place on human life. We hope that compensation will help ease the pain of those who have suffered a loss, even as we recognize that nothing we can do or say can ever bring back their loved ones.

In the case of Iranian victims, we will take appropriate measure to ensure that the money flows directly to the families and not to the government: We will provide none of these funds to the government of the Islamic Republic of Iran. Indeed, we will provide no compensation until mechanisms are in place to ensure that the money goes only to the families of the victims.

Mr. President, the time has come, indeed the time is long past, for us to rededicate ourselves to the cause of peace. The Iran Air tragedy should reinforce our determination to act. It should remind those who would prefer fo ignore the terrible human cost of the Iran-Iraq war and the threat it poses to the security of the Persian Gulf - those who find reasons to delay rather than reasons to act for peace - that their complacency carries a heavy price.

The United States has one overreaching goal in the Persian Gulf. That goal is peace. Peace means cessation of the killing. Peace means total freedom of passage through the straits - total freedom of ships to sail without risk in international waters. Peace also means nations living without the fear of threats or intimidation from their neighbors.

To this end, we will continue to defend our interests and support our friends, while remaining steadfastly neutral in the war. As long as this conflict continues, we and other Western nations will work to contain the threat to freedom of navigation and peaceful commerce in a waterway that is vital to the economies of the world. Our naval presence is welcomed by peaceful nations and is a threat to no one. But we will respond firmly if we are threatened.

The implementation of Resolution 598 would enable the united States to return to the modest naval presence in the gulf we have maintained for more that 40 years, with the support of the gulf states. It would also create new opportunities for a broader international role, perhaps under the auspices of the United Nations, to protect international commerce in the gulf. We look forward to that day.

But make no mistake: Until that day, we will do whatever it takes to maintain freedom of navigation in this vital area of the world, and to take whatever actions we must to protect our forces there. We will not let down our friends and allies. We will not be intimidated by reckless attacks or terror. Our commitment to freedom and peace demands this and nothing less from the United States of America.

Thank you very much.