It does involve sharing sovereignty – but that is necessary in a world where the activities of one state impinge on the freedoms of others. And when it comes to nuclear questions, a successful regime needs to be a global one. That is why I am attending President Obama’s unprecedented Nuclear Security Summit in Washington.

Since the 1960s the world’s approach to nuclear issues has been governed by the Non Proliferation Treaty. It has three pillars – the right to civilian nuclear power, the responsibility of nuclear weapons states to disarm, and the responsibility of non nuclear weapons states not to proliferate nuclear weapons.

The nuclear Security Summit will address the safety of nuclear materials. This is what our Prime Minister Gordon Brown calls the fourth pillar of the nuclear regime. Bringing together 40-plus countries the Summit will chart a course to ensure that nuclear power is used safely to combat climate change and global poverty.

Over the last few years, the UK has been at the forefront of the argument that new momentum was needed to safeguard the gains of the NPT, and address the dangers that are exposed by its weaknesses. We have argued for disarmament and done it ourselves – since 1997 we have cut the number of Britain’s nuclear warheads by 50%. We have argued for safe access to nuclear power – concluding a pathbreaking agreement with the United Arab Emirates. We have made the case for strong sanctions to prevent Iranian access to nuclear materials that would precipitate a nuclear arms race in the Middle East.

After a decade of deadlock on nuclear issues, the agenda is now moving. Last week President Obama and President Medvedev signed a new START Treaty. There is a triple significance to this. First, it reduces US and Russian stockpiles. Second, it shows that multilateral disarmament can work. Third, it takes away the argument that North Korea and Iran can flout their NPT responsibilities because nuclear weapons states are not meeting their disarmament obligations.

President Obama’s Nuclear Security Summit builds on this. We want to see the expansion of nuclear power. It is safe, reliable, and clean – vital in a world fighting dangerous climate change and facing growing energy need.

But for all the benefits of nuclear power, its danger is clear: terrorist groups, principally al qaeda, see the acquisition of a nuclear weapon, or the material and knowledge to build one, as a tempting target. Its record in researching chemical, biological, radiological or nuclear devices is clear.

So there needs to be a global regime to address the danger that new nuclear programmes add to the availability of CBRN material, to tackle trafficking networks for radiological and nuclear materials, to monitor internet availability of CBRN related data, and to control the availability of technical expertise to terrorist groups.

The Summit will establish key nuclear security principles to define the global effort to tackle nuclear terrorism. It will set out how the world should govern its approach to the danger – through an enhanced role for the International Atomic Energy Authority. It will provide for nations to cooperate and learn from each other. And it will seek to reach out to other states.

The first duty of government is to protect the security of its citizens. At home we have created Britain’s first ever National Security Strategy to strengthen our response to fast-moving and interconnected threats, but we will also play a full part in these internationally co-ordinated measures – technologically, through the new National Nuclear Centre of Excellence, and politically through our networks in the UN and around the world.

Our manifesto for 2010 makes clear that we will fight for multilateral disarmament, working for a world free of nuclear weapons, combining support for civilian nuclear energy with concerted action against proliferation, and we will take this work forward in the Nuclear Non Proliferation treaty Review Conference next month.

There is no more important part of the world for global security than the Middle East. All the countries of the region have a role to play in delivering the vision of the Arab Peace Initiative and they have a shared interest in preventing the acquisition of nuclear weapons by Iran. We do not accept the argument that Iran is being asked to forsake rights that are inalienable. All rights are balanced by responsibilities. Iran can be treated as a normal country for nuclear matters if it behaves like one. That means coming clean on its nuclear sites, facilities and processes. Until it does so it is right that we remain 100 per cent committed to a peaceful, diplomatic resolution of the dispute, through engagement but also through sanctions.

In 1997, Britain was a source of despair to its friends and disdain from others. The Conservative government had launched a Beef War on Europe and lost, stood on the sidelines while there was slaughter on the borders of Europe, and cut overseas aid spending.

Today, we are leaders in Europe and at the UN. Our commitments are broad and challenging, but they are driven by clear values and clear interests. In an interdependent world the two come together. We need a government committed to playing its role in the global regime through events such as the Nuclear Security Summit.