I wholeheartedly congratulate my right hon. Friend Dr. Strang on securing this debate. As he rightly pointed out, this issue is one of the most important issues facing our generation, and generations yet to come. What the present generation faces is different from what a slightly older generation faced, but this is a matter of timely concern.

First and foremost, the debate is timely because in Moscow this week President Obama and President Medvedev signed a successor to the strategic arms reduction treaty. Over seven years, it will lead to a fairly dramatic reduction in the number of warheads held by the two countries, limiting each to an arsenal of between 1,500 and 1,675 weapons. That is something we heartily welcome, and which we might not have thought possible two or three years ago.

The debate is also timely because the UK has an extremely strong record in this area. Since the cold war we have reduced our nuclear firepower by 75 per cent. Since 1997, we have reduced the number of warheads by 50 per cent., and I think all Labour Members, and for that matter all members of the Labour party, take particular pride in that. The UK's firepower now represents less than 1 per cent. of the global total. Worldwide figures for nuclear weaponry are now the lowest since the 1950s. Indeed, as my right hon. Friend said, the next five-yearly review conference of the non-proliferation treaty will be in 2010—next year—so it is timely for us to be looking at such issues.

As my right hon. Friend pointed out, there are some strong reasons for a degree of optimism. Not only did we see the agreement between the United States of America and Russia this week, but we also have President Obama's clear and unambiguous pledge to seek ratification of the comprehensive test ban treaty. As my right hon. Friend the Prime Minister pointed out earlier this year, there is probably greater optimism about wider ratification of the treaty than there has been for some considerable time.

Other countries have played a notable role. I single out two. Since Brazil joined the non-proliferation treaty in the 1990s, it has provided energetic leadership around the world, in particular in Latin America. The UK has had a strong, high-level bilateral commitment with Brazil since 2007. Similarly, when South Africa decided to change its position on nuclear weapons, it too took up energetic leadership on such issues around the world, and we want to work closely with South Africa on them. We also have strong bilateral relations with Russia in that regard and are keen to continue that work.

My right hon. Friend was right to point out that early on, before the non-proliferation treaty came into force in 1970, many academics in the UK and around the world believed that by the early 1970s the number of countries with nuclear weapons would rise to between 25 and 30. However, there are now 189 members of the treaty and only three countries stand outside it, so there are reasons for optimism, but as has been pointed out, there are significant reasons for concern too.

Everybody in this country and the rest of the world who has seen the news about North Korea this year is concerned about the situation there. With a second nuclear explosion in May, North Korea has shown open defiance of its obligations. I am glad that the United Nations moved swiftly, and the Security Council provided an unambiguous response. Similarly, Iran continues to enrich uranium in open defiance of numerous Security Council resolutions. Let me make it absolutely plain that we as a country and a Government want further cuts in stockpiles in all countries that retain nuclear weapons.

The world community is presented with a significant new problem, or challenge, by the expansion of nuclear energy. We need to make sure that there is security in the production of fissile material, and that countries moving towards nuclear energy options—often in response to rightful climate change concerns—are doing so for peaceful ends.

There are key issues that we need to address. First, we want a strengthening of the mechanisms and institutions that surrounded the issue of non-proliferation. We want to make sure that there is early and absolutely certain detection of clandestine activity in countries around the world. If we had been able to detect that more certainly in the case of Iran, we might have been able to provide a far clearer and far earlier response from the international community, but we also point out that Iran has no opportunity to move beyond its obligations, and the international community stands firm in response to what Iran has been doing.

We need to strengthen enforcement, because where there is early cognisance of clandestine activity that could be used to move towards producing nuclear weaponry, there should be robust sanctions, as there have been in the cases of North Korea and Iran. There should be tough consequences for those who seek to withdraw from the non-proliferation treaty, and we want to clarify article X of that treaty. We are interested in the proposals that have come from the European Union, and we want to make sure that the clarification goes ahead; we will work with our allies to make sure that it does. It is clearly important that we secure fissile material. One of the greatest dangers to security around the world is the possibility of rogue states or rogue organisations gaining access to fissile material. For that reason, we have doubled our contribution to the funding of the International Atomic Energy Agency nuclear security fund.

The Government believe that the prospects for the comprehensive test ban treaty—an issue raised by my right hon. Friend the Member for Edinburgh, East—and, for that matter, a fissile material cut-off treaty, are brighter than they have been for a good many years. We will continue to make a powerful case for all states to sign up to, and ratify, the comprehensive test ban treaty. We also want talks on a treaty to cap the production of fissile material for explosive military purposes to be under way by early next year. Nationally, we will continue our groundbreaking work with Norway and the non-governmental organisation VERTIC—the Verification Research, Training and Information Centre—on the science of verifying warhead reduction. We will host a conference for the nuclear weapon states on confidence-building measures, including the verification of disarmament, later this year, in September.

My right hon. Friend referred to Trident, as did my hon. Friend Mr. Drew, who is not now in the Chamber. Let me make it clear that the decision made was to begin the concept and design work required to make possible a replacement for our current ballistic missile submarine fleet, and to maintain the option of using the Trident D5 missile beyond its current life expectancy. That does not mean that we have taken an irreversible decision that commits us irrevocably to possessing nuclear weapons for the next 40 to 50 years. Nor does it mean that we have decided to "replace Trident", as my right hon. Friend the Member for Edinburgh, East put it. It is true that, as I have said, we have decided to begin concept and design work to make possible a replacement for the platform, but that is not a replacement for Trident itself. That is not a decision to which we are committed for ever and a day.

Of course, we would be happy, if it seemed appropriate, to place our small proportion of the worldwide nuclear arsenal on the table as part of a multinational process of disarmament. Indeed, we very much hope that there will be further moves towards multinational disarmament, and we would very much want to be part of those negotiations. I point out to my hon. Friend the Member for Stroud that bearing in mind that our nuclear arsenal amounts to a mere 1 per cent. of the global total, we do not believe that a unilateral decision to make it impossible for us to maintain Trident beyond its current life expectancy would make the dramatic difference that some suggest it would.

I am grateful to my right hon. Friend the Member for Edinburgh, East for the opportunity to clarify these matters. I end by quoting from a speech made by my right hon. Friend the Prime Minister earlier this year, when he said:

"Now in 2005 the Non-Proliferation Treaty Review Conference failed. We cannot afford to fail next year"— when the next review conference comes around. He continued:

"So as we approach the 2010 Review Conference I want us to renew and refresh for our times the grand global bargain, the covenant of hope between nations at the heart of the Non-Proliferation Treaty. It is a bargain under which we reaffirm the rights and responsibilities for those countries which forgo nuclear weapons. But it is also a bargain under which there are tough responsibilities to be discharged by nuclear weapon states, for as successor states we cannot expect to successfully exercise moral and political leadership in preventing the proliferation of nuclear weapons if we ourselves do not demonstrate leadership on the question of disarmament of our weapons."

That was what the Prime Minister said earlier this year. We will be publishing soon a document entitled "The Road to 2010", in which we will lay out a credible road map to further disarmament because we, like my right hon. Friend the Member for Edinburgh, East and my hon. Friend the Member for Stroud, want to live in a world that is free of the fear of nuclear weaponry.

Question put and agreed to.

House adjourned.