US President Donald Trump is planning to abandon the Iran nuclear deal shortly, according to US media reports.
If he fails to certify the accord, Congress will decide whether to re-impose economic sanctions on Iran. Mr Trump has until 15 October to decide.
Opposition to the deal was a major part of his campaign last year.
Posing for photographers with military leaders on Thursday, he said this was “the calm before the storm” but refused to give further details.
There was speculation his comments might refer to heightened tensions with North Korea, but the New York Times says “people who have been briefed on the matter” believe he means Iran.
Mr Trump was seen at the White House with his wife Melania, as well as military leaders, after Thursday’s meetings but before dinner together. Gesturing at the people around him, he asked the waiting press if they knew “what this represents”.
“Maybe it’s the calm before the storm,” he said.
When reporters pressed him on what storm he was referring to, he would only say: “You’ll find out.”
He had earlier told his top defence officials he expected them to provide “a broad range of military options… at a much faster pace” in future.
What is the Iran nuclear deal?
The 2015 accord was designed to prevent Iran developing a nuclear weapon, with the president’s administration having to certify to Congress that Iran is upholding its part of the deal every 90 days.
France, Germany, China, Russia and the UK are also partners in the deal.
It lifted some sanctions that stopped Iran from trading on international markets and selling oil.
The lifting of sanctions is dependent on Iran restricting its nuclear programme. It must restrict its uranium stockpile, build no more heavy-water reactors for 15 years, and allow inspectors in to the country.
Mr Trump has repeatedly said Iran has broken the “spirit” of the deal.
In a speech to the UN General Assembly, Mr Trump called the deal, which was brokered while his predecessor Barack Obama was in power, “an embarrassment to the United State”.