Those impacts will only become apparent once America's partners give their own response to Trump's decision, and when details of how the USA measures are implemented are clear, the IG said.
The United States will likely re-impose sanctions against Iran after 180 days, unless some other agreement is reached.
The big question at this point is how disruptive unilateral sanctions from the US will be to Iranian oil flows. Gasoline prices for the 12 months ending in April, meanwhile, are up 13.4 percent.
Meanwhile, Reuters has reported that Iran intends to export its own crude oil in wake of U.S. sanctions against Tehran.
USA investment bank Jefferies said in a note on Friday that it expects Iranian crude oil exports to start falling in the next few months. "Iranian is not the only crude".
US pressure to decrease Iranian oil purchases puts South Korea in an especially tricky position while it is trying to convey to North Korea that it is serious about committing to a denuclearization deal.
The U.S. President Donald Trump on Tuesday afternoon announced the U.S. would violate the Iran nuclear agreement, almost three years after the Joint Comprehensive Plan of Action (JCPOA) was struck.
Production in the United States is surging thanks to the shale revolution. And if South Korea does not find some sort of common ground with the United States, it risks exacerbating a point of friction between two partners that can not afford to be out of lockstep in the messages - both explicit and implicit - being sent in a critical period to Pyongyang.
That is up 27 percent since mid-2016 and means that US output is creeping ever closer to that of top producer Russian Federation, which pumps about 11 million bpd.
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President Donald Trump chose a dicey time to crack down on Iran, the world's fifth-biggest oil producer.
Iran increased its oil production by 1 million barrels per day after sanctions were lifted back in 2016. Already playing catch-up after being caught off-guard by the speed and unconventional nature of recent USA and South Korean diplomacy with North Korea, Japan is simultaneously pursuing a permanent exemption to President Trump's planned aluminum and steel tariffs.
Most analysts believe that at least some nations will ignore the new American sanctions and continue buying Iranian crude.
The EU had essentially cut its oil imports from Iran to zero the first time around, a scenario that probably won't be repeated again since the EU supports the nuclear agreement.
Prices extended gains after U.S. Energy Information Administration data showed domestic crude inventories fell 2.2 million barrels in the latest week, far exceeding forecasts for a decrease of 719,000 barrels.
Outside OPEC, soaring USA crude oil production could help to fill Iran's supply gap.
Other major producers could fill the hole left by Iran. Hours before Trump's announcement, federal government forecasters raised their estimate for 2018 oil prices by 10.5% to an average of $65.58 a barrel. But Europe is unlikely to do so.
No one knows exactly how high prices will go.
The official further noted that Iran's oil industry has gone through massive changes through years and it can not be compared with 20 years ago. What's more, Saudi Arabia has already indicated that it will look to soften any production losses by increasing its own output, so global stock levels may not drop materially. Much of Iran's oil is sold to China, India, and Turkey, all of which are likely to ignore USA sanctions, while Germany, France, the UK, and Russian Federation have all commented that they will not follow the United States' path. Washington can not ensure success alone, particularly because it can not offer sufficient heavy oil exports to compensate for the loss of Iranian heavy oil barrels from the market. Indeed, Saudi energy diplomacy - namely its ability to credibly convince Iranian crude buyers that acquiescence with US policy will not come at economic loss - will be a key determinant of the success or failure of the Trump administration's new course.