Washington (AFP) – The United States on Thursday called for “serious steps” to be taken after Iran resumed uranium enrichment at its underground Fordow plant in a new step back from its commitments under a 2015 nuclear deal.

“Iran’s expansion of proliferation-sensitive activities raises concerns that Iran is positioning itself to have the option of a rapid nuclear breakout,” US Secretary of State Mike Pompeo said in a statement.

“It is now time for all nations to reject this regime’s nuclear extortion and take serious steps to increase pressure.”