The overture, which represents a major and long-considered policy shift by Washington, came in a speech by the US Secretary of State, Madeleine Albright, in New York on Wednesday night and was endorsed by President Clinton yesterday.
Addressing the Asia Society in New York - at one remove from the critical eye of Congressional hawks - Ms Albright said: "We are ready to explore further ways to build mutual confidence and avoid misunderstandings."
She called on "the Islamic Republic" to consider "parallel steps". "The gap between us remains wide," she conceded. "But it is time to test the possibilities for bridging this gap."
Her words, perhaps not coincidentally, came less than a week before football teams from the two countries were due to meet in the World Cup and amounted to the first direct response by the US to an overture from the newly elected Iranian President, Mohammad Khatami, in February.
Mr Khatami had taken the politically bold decision to use a CNN television interview to extend an olive branch to the country his compatriots had dubbed "the Great Satan" and call for dialogue.
Since then, despite occasional hints from Mr Clinton that he favoured a gentler approach to Iran and gave the go-ahead for the resumption of cultural and educational exchanges, State Department and Pentagon officials continued to urge caution.
The State Department, whose diplomats were held hostage in the Tehran embassy in 1979, was especially wary. When pressed about a response to the Iranian overture, officials insisted for the best part of four months that they were studying Mr Khatami's interview, but wanted to see "deeds, not words".
Yesterday, in a first reaction to the US shift, Iran's foreign minister, Kamal Kharrazi, turned those words back on Washington. "Only coming with new words and political words is not enough. I believe words have to be followed by deeds," he said.
While decrying continued US opposition to a Caspian oil pipeline crossing Iran, he acknowledged that "Americans are coming to some new understandings".
With a nod to existing US foreign policy priorities and in clear anticipation of likely domestic opposition, Ms Albright had hedged her opening to Iran with a set of conditions. She called on Iran to halt support for terrorism and criticised its human-rights practices.
But she also welcomed Iran's decision to support any agreement that the Palestinian leader, Yasser Arafat, made with Israel. Tehran's hostility towards Israel has been a big obstacle to the normalisation of US-Iranian relations.
The US policy shift appears to be part of a general reassessment of policy by Washington towards the Persian Gulf region. It has tacitly admitted its policy of confrontation with Iraq has failed for lack of international support, and recently agreed increased funding for Iraqi opposition groups.
Ms Albright's statement that Iran would be welcome to join multinational security operations "if it is willing to make a constructive contribution" showed that, with India and Pakistan now openly possessing a nuclear capability, the US is looking for new security ties in the region.Reuse content