The NPT review conference began as it is likely to continue -- as a struggle between the United States and Iran, writes Graham Usher from the UN President Mahmoud Ahmadinejad took his country's fight with the West over its nuclear programme to a new stage on 3 May: the five-yearly nuclear weapons Non-Proliferation Treaty (NPT) review conference at the United Nations. In a speech studded with pieties and rage, he charged the United States and the five other declared nuclear weapons' states as the world's worst proliferators. The US, France, Britain, Russia and China's "production, stockpiling and qualitative improvement of [their] nuclear armaments now serves as the justification for others to develop their own" nuclear arms, he told delegates, to restrained applause. The NPT is the world's most important pact on nuclear arms, bound both to prevent their spread and ultimately to pursue their elimination. But as a grand bargain between the nuclear weapon states and non-nuclear weapon states it has long been threadbare. Its supporters say since 1968 it has restricted the spread of nuclear weapons to just nine countries: the permanent Security Council members listed above plus India, Pakistan, North Korea and Israel, all of which developed their arsenals outside the NPT. Its detractors say the NPT has not only done nothing to make any of the nuclear weapon states disarm. It has enshrined institutional discrimination between the nuclear "haves" and "have-nots", with one standard for those with nuclear arms and another for those vowing to go without. In fact, "the US government has not only used nuclear weapons but also continues to threaten to use such weapons against other countries, including Iran," said Ahmadinejad. Secretary of State Hillary , who followed Ahmadinejad at the conference, fired back. Iran "is the only country represented in this hall" that has a nuclear programme in violation of both UNSC resolutions and International Atomic Energy Association (IAEA) safeguard obligations, she told delegates. It "has placed the future of the non-proliferation regime in jeopardy". The US-Iran wrestle will likely dominate the month-long conference. In 2005 -- the last time an NPT review was held -- the same struggle helped wreck it. The Bush presidency refused to be bound by any previous disarmament pledges, including support for a 1995 NPT resolution calling for a nuclear-weapon free zone (NWFZ) in the Middle East. Iran decided to enrich uranium for the first time in three years, prompting three UNSC sanctions resolutions against it. The auguries are brighter in 2010. Unlike Bush, Barack Obama has put nuclear disarmament and non-proliferation at the centre of his foreign policy: at the review conference on 3 May he issued a statement revealing that the US had 5,113 nuclear warheads in stockpile, an act of "transparency" he hopes other states will emulate.But -- like Bush -- Obama sees the nuclear programmes of Iran and North Korea as the gravest to the non-proliferation and has done nothing to bring India, Pakistan, and Israel into NPT compliance. Outside the treaty his main thrust has been to marshal a fourth round of UNSC sanctions against Tehran. And at the review conference he wants support for unannounced, compulsory IAEA inspections of the nuclear programmes of states like Iran and automatic penalties for countries that withdraw from the treaty, as North Korea did in 2003. Ahmadinejad's barnstorming was to prevent either coming to pass, says nuclear analyst Rebecca Johnson. "Iran is very anxious not to be criticised in any formal NPT document," she says. "But -- as usual with Ahmadinejad -- whenever he feels under pressure, he attacks. So he will call for total nuclear disarmament and a NWFZ in the Middle East, both longstanding Iranian demands. But his real agenda is not to be stigmatised in any NPT process." Johnson doubts the non-proliferation regime could survive another failure like 2005. But she knows it will be hard to reach consensus between the "haves" and "have- nots", even without the Iran issue. For all Obama's hopes of "a world without nuclear arms" neither the US nor any other nuclear weapon state will submit to a rigid timetable for their elimination, as demanded by the Non-Aligned Movement for example. And not only Iran but also Brazil and Egypt will resist tougher IAEA inspections as infringements of their nuclear rights, especially as no such surveillance is being proposed for the non-NPT nuclear weapon states. But there is one possible area for compromise: revival of the 1995 resolution for a NWFZ in the Middle East. Long championed by Egypt, this was seen as a means of disarming Israel and bringing its nuclear facilities under IAEA scrutiny. The US has said it will support neither move: it accepts the Israeli argument that such measures should happen after advances in a peace process, not before. But Washington may back a pre-treaty conference for a NWFZ in the Middle East and the appointment of a special coordinator to make it happen. After 15 years of dormancy this would represent a shift in the US position, says Ms Johnson. It may even prevent the NPT review conference from again collapsing into competing blocs. "If there's a commitment to hold a conference in the Middle East and appoint a special coordinator to facilitate work on a NWFZ, you'd see a lot of the non-aligned countries leaning on Iran not to block it," she says. The struggle between the US and Iran may in the end boil down to the wording of a final NPT document. Washington is unlikely to support any call for a NWFZ in the Middle East without language about Iran's alleged non- compliance under the NPT. Iran will find it hard to support any call with such language. The final document will show which of the two wields the greater pen.