The US special representative for Iran, Brian Hook, has declined to say what the Trump administration in Washington plans to do when 180-day sanctions waivers granted to eight countries to continue importing Iranian crude oil end in May.

Turkey, Greece, Italy, India, China, Taiwan, Singapore and Japan were granted the waivers in early November when the US introduced heavy sanctions against key Iranian industries, including its oil, gas and petrochemicals sectors. While using the waivers the countries are supposed to work on winding down purchases of Iranian oil. Washington wants to see Iran’s oil exports reduced to zero as it continues with its strategy of throttling the nation’s economy to force Tehran to the table to negotiate concessions on its Middle East activities and policies.

Observers noted the US granted the waivers after anxieties emerged that a hard push for zero exports before it was clear that other oil producers could replace Iranian crude lost to the market might drive up the world oil price, hitting the US motorist among others. The special dispensations given to the eight countries were seen as giving Iran’s economy, pushed back into recession by the US sanctions regime, something of a breather.

While not commenting on possible waiver extensions, Hook did tell an oil industry conference in the United Arab Emirates capital Abu Dhabi on January 12 that the US was not looking to grant more waivers for Iranian oil imports.

“We are not looking to grant any waivers or exemptions to the import of Iranian crude,” Hook said, according to Reuters.

“Iran is now increasingly feeling the economic isolation that our sanctions are imposing ... We do want to deny the regime revenues,” he was also reported as saying, adding: “Eighty percent of Iran’s revenues come from oil exports and this is [the] number one state sponsor of terrorism ... We want to deny this regime the money it needs.”

Hook was also cited as saying that sanctions were choking off Iran’s income streams and that Tehran was “facing a liquidity crisis”.

Separately, Omani Oil Minister Mohammed bin Hamad al-Rumhi reportedly told the conference that Washington had not asked the Gulf Arab state to stop a gas pipeline project with Iran and that talks were continuing.