The most important agreement to come out of the G8 summit was perhaps one from the meetings on the sidelines: the resurrection of India’s nuclear deal with the US . The attraction of the deal, both governments have argued, is that it would supply India with the equipment to build more nuclear power stations, helping it to meet its need for energy, while adding less to carbon emissions. It also allows the US to sell nuclear equipment to a country on its blacklist since India’s 1974 nuclear test.

But the harm done by the deal – which outweighs the value of the help to a large, poor country, many in the US Congress and other governments have argued – is that it contradicts one of the aims of the 1970 Nuclear Non-Proliferation Treaty (NPT). It rewards India with civil nuclear help even though Delhi, which has refused to sign the treaty, acquired nuclear weapons. In doing so, it weakens the treaty’s central bargain: that the original five nuclear powers (the US, UK, France, China and Russia) would help non-nuclear weapons states with civil power provided their ambitions stopped there.

The spread of weapons to countries that never signed the pact has made it hard to justify its value to those that have. Israel’s presumed nuclear weapons capability (the former US President Jimmy Carter told The Times in May that it had 150 nuclear weapons) was the start. The US, after September 11 needing Pakistan’s support, has avoided much censure of its nuclear programme, despite revelations since then that the scientist A. Q. Khan supplied companies that helped Iran, Libya and North Korea to gain expertise. The message it sends is that the US will make exceptions for its friends but wants everyone else to stick to the treaty.

The current dispute between Iran and the UN Security Council shows how difficult that is to monitor or enforce by the International Atomic Energy Agency, the UN watchdog. As technology has improved, the difference between the ability to make fuel for power plants (allowed under the NPT) and fissile material for warheads is close to zero.

For years the five nuclear powers of the treaty have regarded it as too fragile to renegotiate. But the threat of proliferation across the Middle East is raising interest in the idea. Mohamed ElBaradei, the IAEA Director-General, suggested pooling enrichment facilities under international control. In the US, George Schultz, the former Secretary of State, wants cuts in the nuclear stockpiles, as do, in the UK, four former foreign and defence secretaries (Lord Hurd of Westwell, Lord Owen, Lord Robertson of Port Ellen and Sir Malcolm Rifkind).

Even though Manmohan Singh, the Indian Prime Minister, has overcome the immediate obstacles in Parliament, it is still possible that the US-Indian deal will stall in the US Congress. Both countries must persuade the IAEA and the 45-nation Nuclear Suppliers Group, which seeks to curb proliferation by controlling nuclear exports. The Bush Administration may warn Congress that if the IAEA and the group pass the deal but it does not, other countries will get the commercial benefit of selling kit to India. Given the minimum time that Congress needs to debate it, there is a good chance this will become yet another of the urgent decisions facing the next US president.

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