(JNS) U.S. sanctions have caused at least one-quarter of Iran’s oil rigs to be inactive, according to a Reuters report.

“At least 40 of about 160 oil rigs in Iran remain idle or under repair,” reported the outlet, which reviewed information from two industry sources, drilling firms’ websites and quarterly financial findings.

“Some of Iran’s oil rigs are out of action because they can’t be repaired,” according to the Reuters report. “Sanctions have also made it more difficult and expensive for Iran to buy and import spare parts.”

Since the United States withdrew in May 2018 from the 2015 Iran nuclear deal—reimposing sanctions and enacting new ones—and ended waivers the following year for countries importing Iranian oil, Iran’s crude sector has slashed its output by half since early 2018 to less than 2 million barrels daily. It is Tehran’s main source of revenue.

Massive layoffs in the Iranian oil industry have also occurred. North Drilling Company, a private firm that is Iran’s second-largest driller that owns 12 rigs, has 2,800 employees as of 2018, compared to 9,300 in 2017.

The sharp decline in oil prices this year has been exacerbated due to the coronavirus outbreak, which has hit Iran especially hard and is expected to worsen its economy.