Arrogance: U.S. orders allies to cease Iran oil imports by November
The official indicated that there will be no additional phase-out period after the sanctions kick in at the end of the 180 days from when President Donald Trump unilaterally withdraw from the Iran nuclear deal in May. Also, there will likely be no waivers.
"They should be reducing now," the official said, describing the current period as the "drawdown" time.
The move will likely add pressure to rising oil prices, even as US ally Saudi Arabia - a regional rival of Iran - indicated it will increase output. Russia has also signalled it plans to raise production levels.
The pressure on Iran comes as the US goes after key allies on trade - slapping tariffs on Canada, Europe and other partners - while also threatening more action against rivals, such as China.
At the same time, the U.S. is also hoping for Chinese cooperation on North Korea, which Washington wants to see abandon its nuclear weapons programme.
The official, speaking on background, said the administration had yet to hold talks with China, India and Turkey.
Beijing and New Delhi would be vital to make the sanctions on Tehran bite, but there have been indications those growing economies, hungry for energy, are not going to suddenly cut supplies.
To skirt sanctions countries can try to do deals that avoid using US dollars.
Japan had already indicated to the US that it is "difficult" to cut out Iranian oil, the official said, but insisted US allies realize the White House is "not kidding" about its efforts to sanction Iran and apply secondary sanctions to those who import oil.
The US is pursuing what it describes as a maximum pressure campaign against Iran
The State Department official pointed to protests in Iran and expressed confidence that there was growing anger against the government.
"Every month it seems there is a new protest erupting over a new cause," the official said. "Iranians are basically fed up with the regime squandering the nation's wealth" on operations abroad, the official said.
Iran is deeply involved in Syria, for example, and also supports militants groups elsewhere, including in Yemen.
Tehran's regional activity is a source of concern for Saudi Arabia and the U.S. administration, with Washington arguing the nuclear deal freed up Iran to engage with more projects outside its borders.
The White House seems to be hoping its sanctions would help add to the pressure on the government.
Washington and Tehran have been at odds since the Islamic revolution in 1979.
US allies in Europe are upset Washington withdrew from the deal, negotiated under Trump's predecessor Barack Obama, saying it was achieving its goal of preventing Tehran from obtaining nuclear weapons.
When Obama sought to increase pressure on Iran ahead of the nuclear deal being reached in 2015 he was able to rely on US allies and even China to reduce economic links to Iran. Trump's tensions with trading partners could hamper cooperation.
However, some companies have already started to reduce their presence in Iran, fearing tough US sanctions. ■