Iranian crude oil exports have declined to around 400,000 barrels per day (b/d) in May, according to tanker data and industry sources, Reuters reported.

The drop in exports has been mainly caused by the US re-imposing sanctions on Tehran and then ending sanction waivers for major Iranian oil buyers.

“I am expecting exports of about 400,000 b/d,” one of the sources said, up from the 250,000 b/d exported in the first two weeks of May. On the other hand, the second source commented that May exports might reach as much as 500,000 b/d.

American sanctions led to a drop in Iranian crude exports from 2.8 million b/d to around 1 million b/d in a year’s time.