Sanctions have achieved nothing with Burma and should be replaced by dialogue, the US secretary of state, Hillary Clinton, said early last week. Sanctions are essential and should be increased on Iran, said Barack Obama at the end of the week in which it was revealed the country had established a secret additional site for enriching uranium.

Little could so demonstrate the double standards and the particular distrust with which Iran is treated in international affairs than this contrast. The latest Iranian admission only adds fuel to a furious row of charge and counter-charge that has been busily stoked up by Israel, some of Iran's Arab neighbours and the US right. "Iran's nuclear programme is the most urgent proliferation challenge that the world faces today," said Gordon Brown at the UN last Thursday, adding from Pittsburgh on Friday that there "was no choice but to draw a line in the sand".

Even taking into account the British prime minister's desire to push himself to the forefront of international events to impress voters, this is verging on hyperbole, and will do little to improve the tenor of talks between Iran and the members of the Security Council, plus Germany, on Friday.

The problem is both that Iran is a particularly difficult country to deal with, especially after the re-election of its radical president Mahmoud Ahmadinejad, and that its ambitions and its willingness to compromise are so uncertain. Iran's leaders are adamant its intentions in developing nuclear technology and uranium enrichment are only for peaceful purposes. It remains a signatory of the nuclear non-proliferation treaty, which allows it to enrich uranium as fuel. It has also accepted, but not given total free access to, inspectors from the UN's Atomic Energy Agency (IAEA).

The west, led by Washington and spurred on by Israel, suspects all this is just a ruse behind which Iran is secretly planning a weapons programme and it points to evidence from the IAEA that Iran has hidden various developments from oversight.

The admission by Tehran of its covert enrichment facility is certainly an embarrassment to the regime but doesn't prove the case either way.

Just as Israel has based its security on perceived threats from its Arab neighbours, so Iran's attitude has been forged by the constant assaults of its neighbours and the west. It may well be that it wishes to have command of the technology of nuclear weapons without actually developing them. Even at that, it is still uncertain how much of a threat they would be. Opinion is divided on how quickly it could develop the processing capacity to convert low-enriched uranium to the levels required for weapons, while the US has just put back its estimates of Iran's ability or interest in long-range missiles well into the future.

The chief concern at the moment must be that, by ramping up the rhetoric at this time, the US and its allies will harden Iran's resolve to pursue its nuclear programme rather than obey UN resolutions.

This could be the beginning of a long process. But it could also precipitate a real international disaster, leading to everyone's worst fears being realised.