US President Donald Trump has tweeted he will announce his decision on whether to withdraw from the Iran nuclear deal tomorrow.
Mr Trump has until 12 May to decide whether or not to remain in the 2015 international deal, which provides Iran with relief from sanctions in exchange for limiting its uranium enrichment capacity.
He has been highly critical of the agreement, saying the US will withdraw unless European signatories fix, what he has called, its serious shortcomings.
The announcement will be made about 6am tomorrow (NZT).
I will be announcing my decision on the Iran Deal tomorrow from the White House at 2:00pm.— Donald J. Trump (@realDonaldTrump) May 7, 2018
Ending US sanctions relief could also trigger a backlash by Iran, which could resume its nuclear arms program or punish US allies in Syria, Iraq, Yemen and Lebanon, diplomats said.
It remains unclear how Mr Trump will proceed with a potential withdrawal, two White House officials told Reuters last week.
One of the White House officials said it was possible Mr Trump will end up with a decision that "is not a full pullout," but was unable to describe what that might look like.
Under the agreement with the US, France, Germany, Britain, Russia and China, Iran strictly limited uranium enrichment capacity to try to show that it was not trying to develop atomic bombs. In exchange, Iran received relief from economic sanctions.
Regardless of what Mr Trump decides on the deal, Iranian President Hassan Rouhani said Tehran could remain in the agreement and would fiercely resist US pressure to limit its influence in the Middle East.
"We are not worried about America's cruel decisions ... We are prepared for all scenarios and no change will occur in our lives next week," Mr Rouhani said in a speech broadcast live on state TV.
"If we can get what we want from a deal without America, then Iran will continue to remain committed to the deal. What Iran wants is our interests to be guaranteed by its non-American signatories ... In that case, getting rid of America's mischievous presence will be fine for Iran."
Britain, France and Germany remain committed to the accord and, in an effort to address US complaints, want to open talks on Iran's ballistic missile program, its nuclear activities beyond 2025 - when pivotal provisions of the deal expire - and its role in the wars in Syria and Yemen.
British Foreign Secretary Boris Johnson, in Washington for talks this week, said the deal had weaknesses but these could be remedied.
"At this moment Britain is working alongside the Trump administration and our French and German allies to ensure that they are," he said in a commentary in the New York Times.
Mr Johnson met US Secretary of State Mike Pompeo and Vice President Mike Pence on Monday.