In the post-war period the US and Soviet Union developed a mutual standoff, known - some thought appropriately - as MAD (Mutual Assured Destruction).
Horrifying though this concept may appear, it actually worked, saving the world from destruction, even though at the time of the Cuban crisis over 40 years ago it did so by a very narrow margin indeed.
In the 1970s, however, Nato's unpreparedness to finance an adequate conventional defence led it to develop the concept of using tactical nuclear weapons to halt a possible Soviet conventional attack on western Europe.
At the time it seemed to me difficult to justify resorting to nuclear weapons simply because it cost less than raising adequate conventional forces to resist a Soviet conventional attack. But as domestic public opinion in Ireland had precluded any Irish contribution whatever to western conventional defence, we were in no position to make that point.
Ireland has a particular interest in nuclear non-proliferation, because in 1958 our foreign minister, Frank Aiken, made this issue his own at the UN - to such effect that within three years a resolution in favour of a nuclear non-proliferation treaty proposed by him had been adopted by the General Assembly. And when such a treaty was finally negotiated in 1968, in recognition of Aiken's efforts he was invited to Moscow to be the first to sign it.
In the event, this treaty has since been ignored by Israel, India, Pakistan and, most recently, North Korea, all of which have developed such weapons.
At various points during the intervening decades several other countries have been reported to have initiated similar projects, but have eventually abandoned these schemes under external pressure - which in the case of Iraq took the extreme form of the bombing of its nuclear plants by Israel.
The failure of the permanent members of the Security Council to challenge flagrant Israeli, Pakistani or Indian breaches of the Nuclear Non-Proliferation Treaty has clearly weakened these powers' moral authority to mount a challenge to later breaches, such as those now apparently threatened by North Korea or Iran.
In the case of North Korea the fact that this "rogue" state appears to have succeeded in constructing a small number of such weapons secretly has effectively inhibited action against that state, and the western powers are currently concentrating their efforts on an attempt to stop Iran from achieving a similar outcome.
Various arguments have been advanced against this western approach. Linda Heard argued last Wednesday in Arab News that it is inconsistent to propose to bring Iran's nuclear policy before the Security Council when North Korea is being handled with kid gloves, and when no such action has ever been taken against Israel, India or Pakistan, the latter of which actually sold nuclear arms technology to other states for hard cash.
It is not easy to counter this argument, although the fact that the president of Iran has actually publicly threatened Israel with destruction has certainly added an important new factor to the Iranian equation.
It has also been argued that there is no hard proof that Iran is actually trying to develop nuclear weapons. However, the fact that it has failed to accept a Russian offer to provide it with enriched uranium for civil purposes strongly suggests that the Iranians have a weapons agenda.
When Britain, France and Germany initiated their approach to Iran in November 2004, this included a proposal that an objective Iranian guarantee against the development by that country of nuclear weapons could be matched by "firm commitments" on security issues, viz guarantees against a US attack on Iran.
However, in The Irish Times of Saturday last Selig Harrison of the Centre for International Policy suggested that the US has been unwilling to co-operate with the EU in formulating such guarantees.
There is a theory that in taking up its present negative stance Iran might be seeking to break such a deadlock, so as to secure the dropping of the long-established US boycott of Iran and a guarantee that the US would not use force against that country.
If such is the case, the Iranian president's threat to Israel has effectively sabotaged any such move. High-wire tactics of this kind can sometimes prove dangerous to those who adopt them.
However, it can be also argued that this Iranian crisis might never have arisen if the western powers had not decades ago allowed Israel to develop nuclear weapons in defiance of the treaty. Why did they fail to tackle this Israeli move?
Perhaps I can throw a little light on this. Some 16 years ago I was asked to prepare a study of the Israel-Palestine crisis. Before going to the region to meet the Israeli government and politicians as well as Palestinian leaders including Yasser Arafat, I visited Washington, London, Paris, Rome and Tokyo to get the views of interested governments. And I also met Nato officials in Brussels.
I asked these latter officials bluntly why their organisation had remained silent about the Israeli development of nuclear weapons in defiance of the Nuclear Non-Proliferation Treaty. After some shuffling of feet, the answer I elicited was a somewhat shamefaced "Well, the Israelis were kind of allies of ours, you know."
In the published report on my mission I felt it appropriate to refer to "the existence of an Israeli nuclear capacity", adding that "Israel is now thought to have well over 100 nuclear weapons". But when I presented this report at a meeting in Washington in April 1990, an "informed US source" told the meeting that I had underestimated the Israeli nuclear capacity, which he suggested was then about 150 nuclear weapons, "and they are working on a hydrogen bomb".
It is, of course, not surprising that the Israelis should have decided to attempt to develop a nuclear weapons capacity, given the fact that they had lost six million of their relations in the Holocaust, and that they were surrounded by, and had three times in a quarter of a century been involved in armed conflict with, heavily-armed neighbours. More-over, some of their neighbours' leaders have made no secret of their desire to wipe out this tiny state.
It was self-evident that nuclear protection was bound to be an Israeli aspiration. But, given that it was equally self-evident that such an Israeli initiative was bound to evoke from one or other of the hostile states in the region an ambition to match Israel in nuclear terms, the failure of the western powers to challenge Israel's acquisition of such a capacity is difficult to defend.
The present dilemma over how to handle Iran's threatening nuclear ambitions finds its roots in that profound failure of western diplomacy back in the 1960s and 1970s.