US and Iran nuclear talks at critical stage amid threat of Trump tearing up terms of success

Tehran says deal is possible as long as Washington abides by agreed-on preconditions, but Trump's view is unclear

Iran enters critical talks on its nuclear programme with the US on Thursday, insisting a deal is in reach as long as Washington sticks by its willingness to concede Iran's symbolic right to enrich uranium, allow Tehran to dilute its stockpile of highly enriched uranium in country, and not to impose controls on Iran's ballistic missile programme.

The three preconditions for success are seen as critical by Iranian diplomats, but it remains unclear whether Trump accepts these parameters.