The U.S. has repeatedly vowed to take Iran's oil exports to zero, and has maintained that any waivers would be "few and far between", as National Security Advisor John Bolton put it.
"Houston's importance as a trading and export hub for physical crude oil from Cushing and the Permian Basin continues to evolve due to the shale oil revolution and repeal of the crude oil export ban", Peter Keavey, CME Group Global Head of Energy, said in September.
The US has asked many countries including India to bring the oil imports to "zero" level from the Gulf nation by November 4 this year or face the effect of sanctions.
The country made the decision to cut its oil imports long before USA sanctions against Iran take effect in November 4.
Washington's plan to impose sanctions on Iranian crude could strain already soured ties between the United States and Turkey - at odds over a host of issues from diverging interests in Syria to Ankara's ambition of buying Russian defense systems.
The government is to offer oil in the form of at least 35,000-barrel-cargos and the total of one million barrels per day at IRENEX, he announced addressing the 4th Iranian Petroleum and Energy Club Congress & Exhibition in Tehran.
More seriously for Saudi Arabia and other Arab oil producers, the surge in prices, which rose again after the Iranian revolution in 1979, resulted in permanent demand destruction and encouragement of alternative suppliers.
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The WTI Crude Oil market initially tried to rally during the week but then broke down through the $70 handle, a significant technical and psychological level.
Exports of Iranian crude oil have been in jeopardy since the White House announced that it is re-imposing unilateral sanctions against the Islamic Republic.
There has been indication that India may not totally stop import of crude oil from Iran.
"In the end, the impact could be higher, or it could be lower", Wittner wrote.
Oil prices had been rising this week on concern about a decline in Iranian exports due to US sanctions, which kick in on November 4, and tension between the U.S.0 and Saudi Arabia after the disappearance of Saudi journalist Jamal Khashoggi.
Saudi Arabia said this month it would ramp up production by 300,000 barrels per day to help offset a sharp reduction of Iran's crude exports next month.
Global oil supplies had already become tight, even before the decisions to cut production and embargo the United States, mostly as a result of low real prices during the 1950s and 1960s. "Price action and discovery suggests traders are no longer concerned about how high prices will go but rather how quickly they will fall". This week, data from the EIA showed that the inventories had climbed to more than 9.5 million barrels. The oil market appears to have little room for error right now.
Finally, Saudi Arabia relies heavily on the United States for security (including the provision of advanced weapons systems, training, intelligence and thousands of USA personnel and aircraft stationed in and around the Gulf).