RFERL:

Iran’s crude oil production plunged to 2.754 million barrels per day (mb/d) in January 2019, about 1.064 million barrels per day less than in May 2018, when the United States withdrew from the 2015 nuclear agreement, OPEC said February 12.

Iran’s January oil production is the lowest level since October 2014, during the tightest period of previous round of international sanctions (2012-2016), imposed on Iran’s oil exports.

The reason for the decline in production is Iran's inability to export its oil and oil products in the face of U.S> sanctions.

Although the U.S. reimposed oil export sanctions last November, it gave a six-month exemption or wavier to eight friendly countries: China, India, Japan, South Korea, Taiwan, Turkey, Italy and Greece to continue buying a restricted quantity of Iranian oil, but it is uncertain if Washington will extend the waivers beyond May.

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