Explained: Iran’s nuclear program as 2015 deal unravels

President Donald Trump, who campaigned on a promise of tearing up the deal because it didn't address Iran's ballistic missile program or its involvement in regional conflicts, withdrew America from the accord in May 2018.

Under terms of the nuclear deal, Iran can keep a stockpile of no more than 300 kilograms (661 pounds) of low-enriched uranium.

Iran announced Sunday it will raise its enrichment of uranium, breaking another limit of its faltering 2015 nuclear deal with world powers and further heightening tensions between Tehran and the US. Iran made the decision a year after President Donald Trump unilaterally withdrew from the deal. Iran has repeatedly warned Europe in recent weeks that it would begin walking away from an accord neutered by a maximalist American campaign of sanctions that blocked Tehran’s oil sales abroad and targeted its top officials.