WASHINGTON, March 22 (Reuters) – The United States reserves the right to take action against any person helping Iran evade U.S. sanctions on energy shipments, a State Department official said on Friday.

The official, who spoke on condition of anonymity, was responding to a request for comment on a Reuters report this week that at least two tankers have sent Iranian fuel oil to Asia in recent months despite U.S. sanctions against such shipments.

“The United States, in cooperation with our allies and partners, is closely monitoring efforts by the Iranian regime to evade U.S. sanctions,” said the official. Washington “reserves the right to designate any person engaging in or facilitating these activities in accordance with our laws.”

President Donald Trump last year abandoned a 2015 nuclear agreement between Iran and six world powers. In November, his administration reimposed sanctions on Iran‘s energy exports to cut off the country’s main source of revenue.

Trump aims to use the sanctions to pressure Iran over not only its nuclear program, but now also its ballistic missile program and backing of militants in Syria and other Middle Eastern countries.

The shipments in question were loaded onto tankers with documents showing the fuel oil was Iraqi. But three Iraqi oil industry sources and Prakash Vakkayil, a manager at United Arab Emirates (UAE) shipping services firm Yacht International Co, said the papers were forged. The shipments show how some traders have revived tactics that were used to skirt sanctions against Iran between 2012 and 2016.

A State Department official recently told Voice of America, a news organization funded by the U.S. government, that the Trump administration would go after anyone conducting off-coast ship-to-ship transfers of Iranian oil and is working with foreign governments to monitor the behavior.

David Peyman, the deputy assistant secretary of state for counter threat finance and sanctions, said U.S. authorities will take actions against ship owners, managers, insurance providers and mortgagees linked to ships involved.

“If you are engaged in evasive action, which is really the worst kind of violation when it comes to U.S. sanctions, we will hold you accountable,” Peyman told the VOA.

(Reporting by Timothy Gardner; editing by Jonathan Oatis)