The United States on Tuesday accused Iran of “nuclear extortion” and vowed no let-up in pressure after the clerical regime, saying it would resume uranium enrichment at the key Fordow plant.

According to State Department spokesperson,” Iran has no credible reason to expand its uranium enrichment program, at the Fordow facility or elsewhere, other than a clear attempt at nuclear extortion that will only deepen its political and economic isolation”.

“We will continue to impose maximum pressure on the regime until it abandons its destabilizing behaviour, including proliferation-sensitive work”, the spokesperson added.

“Maximum pressure” on Iran would continue to be exerted, the spokesperson said, adding that “until it abandons its destabilizing behaviour, including proliferation-sensitive work”.

Rohani announced Iran’s latest step away from commitments to the nuclear agreement since the United States withdrew from it more than a year ago in an address carried live by Iranian state TV.

The move comes a day after Iran announced it was now operating twice as many advanced IR-6 centrifuges that can enrich uranium more efficiently, and that it had a prototype IR-9 centrifuge that works 50 times faster than those allowed under the pact.

Earlier in the month, the US government had imposed sanctions on Iran’s construction sector and the transfer of four materials related to Tehran’s nuclear or military programmes.

Earlier in September, the US imposed its first-ever sanctions against Iran’s space agency, accusing it of disguising a missile program.

The US also warned the “international scientific community that collaborating with Iran on space launch vehicles could contribute to its ballistic missile program.”

In response to the US, Iran had said that its space program is aimed at building rockets to launch telecommunications satellites. Iran has fired two such satellites into orbit since 2013. But three other attempts this year have failed, including one rocket that blew up on the launchpad.

In May this year, President Trump withdrew the US from the 2015 nuclear pact between Tehran and six world powers and has since reimposed and expanded punishing sanctions as part of a stated campaign of “maximum pressure” against Iran.

Iran’s latest move is the country’s fourth step in reducing its nuclear obligations, Rohani said.

The Iranian president insisted that all of the steps his country had taken to reduce its commitments to the nuclear agreement were “reversible.”

Iranian officials have stressed that for any talks with the US, Washington should return to Tehran’s nuclear deal from which it withdrew in 2018 and implement its obligation under the accord.

Following the exit from the Iran nuclear deal, President Trump’s administration has kept piling up pressure on Iran through a series of sanctions and designations, which have been strongly opposed and criticized by Tehran.