WASHINGTON — While a top aide complained of “nuclear blackmail,” Secretary of State Mike Pompeo said today that the United States would wait and see what Iran actually does after it notified the remaining parties to the 2015 nuclear deal that it would temporarily suspend abiding by caps on its stockpile of low enriched uranium and heavy water. Iran could take other measures in two months’ time if the other parties do not find a way for it to get economic benefits to stay in the deal, Iran said, but would return to those limits if they did.

“We will never be held hostage to the Iran regime’s nuclear blackmail,” Brian Hook, the US special representative for Iran, told journalists on a call today marking the one-year anniversary of the US withdrawal from the Iran nuclear deal.

The measures Iran announced in formal letters from Iranian President Hassan Rouhani to France, the United Kingdom, Germany, Russia and China were not seen as a near-term proliferation risk, arms control experts said. But they raised the specter that the “maximum pressure” campaign President Donald Trump imposed when he quit the deal last year could finally drive Iran to breach the arms control pact in the coming months and unravel it.

“I think [Rouhani’s letter] was intentionally ambiguous and we will have to wait to see what Iran's actions actually are,” Pompeo said at a joint news conference with British Foreign Secretary Jeremy Hunt in London today. “They have made a number of statements threatening actions to get the world to jump and we will see what they do. … And when they do we will make good decisions.”