The US says it had no role in a power cut at an Iranian nuclear site and declined to comment on whether Israeli sabotage was to blame or whether the incident might impair efforts to revive the 2015 Iran nuclear deal. "The US was not involved in any manner," White House press secretary Jen Psaki said in response to questions. "We have nothing to add on speculation about the causes or the impacts." Iran accused arch-rival Israel of <a href="https://www.thenationalnews.com/mena/iran-says-incident-at-nuclear-enrichment-site-is-sabotage-and-reserves-right-to-respond-1.1201161">sabotaging the Natanz uranium enrichment plant</a> and vowed revenge for an attack that appeared to be latest episode in a long-running covert war. Israel opposes Tehran's 2015 nuclear deal with major powers, an accord that Iran and US President Joe Biden are trying to revive after his predecessor, Donald Trump, abandoned it three years ago. Israel, whose existence Iran does not recognise, has yet to formally comment, but Israeli media quoting unidentified intelligence sources said Israel's Mossad spy service successfully sabotaged the underground complex. Iran and the major powers described as "constructive" the talks last week to salvage the nuclear deal, whose core bargain involved limiting Iran's nuclear activities in return for the lifting of sanctions by the US and other powers. Mr Trump reneged on the pact in 2018 by reimposing harsh US economic sanctions, prompting Iran to breach many of the nuclear restrictions from 2019. The indirect talks in Vienna, in which mainly European diplomats are shuttling between the remaining parties to the deal and the United States, are expected to resume on Wednesday. Ms Psaki said she expected them to be "difficult and long". "We have not been given any indication about a change in participation [by Iran]." A US official said Washington had no reason to believe Tehran would change its approach because of the Natanz incident, but added "it's too soon to say". He also echoed the view expressed last week by a senior State Department official that Tehran's demands that Washington remove all sanctions imposed by the Trump administration since 2017 would lead to an impasse. "If their position is… we have to lift everything, and we have to lift it up front, and then they verify it, and then they take their first step, that's a recipe for paralysis," he said. "We hope that they will take a more pragmatic approach." <strong>Latest Iran stories</strong>