IF there was even one occasion in the past when the use of a nuclear weapon was justified, it would be foolish and irresponsible ever to get rid of them, since there is no way of knowing when and where a similar set of circumstances might not arise and their use would once again be ''necessary''. Thus every country in the world should have atom bombs, forever.

It follows that our judgment of Hiroshima and Nagasaki is not merely a dispute about a past event but a matter of utmost relevance regarding the conduct of this and every other country in the world now and in the future.

The common justification, as repeated by your correspondents Alastair Stirrat and Colin Cameron (January 15), is that the use of the atom bombs shortened the war and saved Allied lives. There are two replies to this argument.

First, and most important, it must be recognised that even if this were historically factual, it would not justify the use of the bomb. The end does not justify the means. The deliberate targeting of the civilian population is always a war crime. It is not permitted even if it is believed to bring victory nearer.

If it were permissible, then the logical conclusion is that we should keep all our soldiers in their barracks, and annihilate the enemy population en masse. That way, any war could be reduced to a day or two, and our casualties eliminated altogether.

We have no doubts that those who killed civilians during the war in former Yugoslavia are war criminals; we cannot act on the assumption that we are exempt from the same rules of war because we are British.

If Allied troops had systematically made their way through the streets of Hiroshima with flamethrowers and incinerated every man, woman, and child in sight, who would attempt to justify such a war crime? But because the bomb makes a distance - literally - between cause and effect, agent and action, guilt is denied.

Secondly, the belief that using the bomb shortened the war is contradicted by serious historical analysis. Having invested astronomical sums in the Manhattan Project, there was no way the US Government was not going to use the bomb.

This commitment to actual use necessitated evading any possibility of accepting surrender until such time as the bomb could be dropped. This meant a prolongation of the war and a consequential increase in Allied casualties. Let me produce some very reputable military witnesses for this interpretation.

In Volume VI of his History of the Second World War, Winston Churchill writes: ''It would be a mistake to suppose that the fate of Japan was settled by the atomic bomb. Her defeat was certain before the first bomb fell and was brought about by overwhelming maritime power''.

Field-Marshal Montgomery wrote in his History of Warfare: ''It was unnecessary to drop the two atomic bombs on Japan in August 1945, and I cannot think it was right to do so . . . the dropping of the bombs was a major political blunder and is a prime example of the declining standards of the conduct of modern war''.

General Eisenhower himself said: ''Japan was at that very moment seeking some way to surrender with minimum loss of face. It wasn't necessary to hit them with that awful thing''.

Truman's Chief of Staff, Admiral Leahy, wrote: ''It is my opinion that the use of this barbarous weapon at Hiroshima and Nagasaki was of no material assistance in our war against Japan. The Japanese were already defeated and ready to surrender because of the effective blockade and the successful bombing with conventional weapons . . . In being the first to use it, we adopted an ethical standard common to the Dark Ages. I was not taught to make war in this fashion, and wars cannot be won by destroying women and children''.

Nor can the use of the atomic bombs be justified by evoking racist stereotypes of Japanese fanatics fighting on regardless of orders to surrender. Bushido, the Japanese military code, demanded absolute unquestioning obedience every bit as much as it did bravery. If the Emperor says surrender, then that is what must be done, at once and without question.

After the surrender of Nazi Germany in May, it was obvious to all that Japan was doomed. By late 1945, Japan did not have one single plane left, and American pilots could fly and bomb at will. Tokyo, Nagoya, Osaka, Kobe, Yokohama were already utterly destroyed. Japan was defeated, on the point of surrender, and known to be so.

The Japanese Foreign Office had officially notified Moscow on May 13 that ''the Emperor is desirous of peace''.

The Soviet Union ignored these moves because under the Yalta agreement it was due to enter the war against Japan three months after the surrender of Germany, and it was keen to do so.

US intelligence knew of these approaches to Moscow. Work on the Manhattan Project was speeded up in fear that Japan might surrender before the bomb could be used.

The two target cities had been left undamaged throughout the war because they were already selected for the ''experiment'' - the actual word used by Truman and Major Groves (head of the Manhattan Project) at the time.

On August 8 the Soviet Union declared war on Japan, and invaded Manchuria. A Soviet invasion of mainland Japan was now a distinct possibility. This would have meant a joint occupation, as in Germany. It was the determination to prevent this that caused the Americans to accept now the continuance of the Emperor as Head of State - the one and only condition which the Japanese had been asking for since May - and also induced the Japanese to accept the humiliation of a formal unconditional surrender.

The use of the bomb was not so much the final act in the Second World War, as a spectacular demonstration of American power in the opening moves of the new Cold War. Indeed, the then US Secretary of War, Stimson, admitted that the bomb was used ''to get a political advantage over the Soviet Union in the post-war situation''.

The widespread national comfort-myth about the use of the atom bomb must be abandoned once and forever. Hiroshima was our nuclear Original Sin. We will never be at peace with ourselves and with the world until we find the honesty and courage to admit our guilt, apologise to the Japanese people, and forever forswear any threat to repeat such an appalling war crime.

Brian Quail,

2 Hyndland Avenue, Glasgow.

January 19.

CAN'T Stewart Lamont (January 10) see that executing a murderer or letting a convicted murderer go free at the end of his prison term to kill again is somewhat different from the incinerating and torturous violence of the planned detonation of 100 kiloton A-bombs over cities full of innocent children?

There are some issues such as homosexuality, the death penalty, conventional warfare against soldiers and not civilians, nuclear power perhaps in the short term, where Christians can apply relativistic, moral reasoning.

There are others where because of the intensity of deliberate infliction of innocent human suffering and sheer magnitude, like paedeophillia, the Nazi Holocaust, and continuing to possess the bomb - in total disregard for how the political situation has changed, as there is no threat to Britain whatsoever - there must be moral absolutes.

If it is a moral absolute not to have sex with children, should it not also be a moral absolute to not kill them, and we must have killed more than 1000 children in the Gulf war?

As for euphemistic door-locks, is David Rowan Henderson (January 10) aware how close we came to frying the northern hemisphere on a dozen occasions? Leaving aside the Cuban, Suez, and Berlin crises, is he aware of the false radar detections of 1979 and 1980, the incident, recently dramatised for TV, in 1986 in which a fire in the missile chamber of a Yankee-class Soviet SLBM sub nearly caused an accidental launch, and the Americans fired a torpedo at the submarine and the entire Atlantic coast went to DEFCON 2 (The Day America Nearly Died).

What we have is not a door-lock but 100- kiloton landmines under our doormats.

Jonathan Rees,

100 Pollok Drive,

Bishopbriggs.

January 17.