US vows ‘strongest sanctions in history’ on Iran
US Secretary of State Mike Pompeo has said the US is imposing the "strongest sanctions in history" on Iran.
In a speech in Washington, America's top diplomat said Iran would be "battling to keep its economy alive" after the sanctions took effect.
Iran's President Hassan Rouhani responded that the US could no longer decide what the rest of the world did.
Earlier this month, President Donald Trump took the US out of the landmark 2015 Iran nuclear deal.
US sanctions lifted after the 2015 deal will be re-imposed, Mr Pompeo said, and those and new measures will together constitute "unprecedented financial pressure on the Iranian regime".
The older American sanctions prohibited almost all trade with Iran, making some exceptions only for activity "intended to benefit the Iranian people" such as the export of medical and agricultural equipment.
The secretary of state did not say what new measures Washington was contemplating but he described sanctions imposed last week on the head of Iran's central bank as "just the beginning".
Some of Europe's biggest firms who rushed to do business with Iran after the nuclear deal now find themselves forced to choose between investing there or trading with the US.
Some of the biggest contracts at risk include:
French energy giant Total's deal, worth up to 5 billion dollars, signed to help Iran develop the world's largest gas field. Total now plans to unwind those operations by November unless the US grants it a waiver
Norwegian firm Saga Energy's 3 billion dollars deal to build solar power plants
An Airbus deal to sell 100 jets to Iran Air
Iran is one of the world's largest oil producers, and the export of oil and gas is worth billions of dollars each year.
Both the country's oil output and its GDP fell noticeably under international sanctions.