Clare Short: A new nuclear weapon is irrelevant to the real issues

However, a debate has been promised and, given that even Michael Portillo, a former Conservative defence secretary, thinks there's no point in replacing Trident, it will be interesting to see whether the Parliamentary Labour Party (PLP) is willing to swallow this alongside so many other policies that fly in the face of Labour's history and values.

One of the saddest things about the broken state of British politics is the way in which the spirit of the Labour Party has been undermined by Blair. For so many local members, there is no point in staying to fight because the party's internal democratic system has been crushed. The PLP has been kept in line by large majorities, traditions of loyalty, the lure of patronage and the power of the whips. There is enormous unhappiness in the PLP, but the question is, is there a breaking point?

The political case against the replacement of Trident is overwhelmingly strong. To address it, we need to ask what role we want our country to play on the world stage. Should we continue to act as a fig leaf for the US and pretend that a nuclear weapon supplied and serviced by them somehow makes us a significant power? Or do we understand that the threat of global warming, the growth of the world population, and the loss of environmental resources is the most important threat to the future of human civilisation?

Our most urgent need is to create global agreement to reduce carbon dioxide emissions and create a new economic model based on greater equity and a more sustainable economic system. The honourable role for the UK is to work with others to reinforce respect for international law, strengthen multilateral institutions, promote peace and security and sustainable development worldwide. A new nuclear weapon is irrelevant to this.

There is also a strong argument that a weapon to replace Trident would breach the non-proliferation treaty. The treaty obliges the nuclear weapon states to reduce and then eliminate nuclear weapons.

There is no point in spending large quantities of money to buy a new nuclear weapon which is targeted at no one to feed the delusion that the UK is a great power. There would be no prospect of the UK using it without US approval. If the UK replaces Trident, we will be locked into the role of US poodle for another generation.

The important question is whether enough Labour MPs will feel that this is their breaking point with Blair.

The author is a former secretary of state for international development