The United States on Thursday announced a new wave of sanctions targeting Iranian or Iran-linked shipping and petrochemical companies.

The sanctions include two shipping firms based in China, the Treasury Department's website showed.

The sanctions also target 20 shipping vessels linked to firms in China, Vietnam, and the United Arab Emirates, the website showed.

The website did provide details on the new sanctions. A Treasury spokesperson referred questions to the State Department, which did not immediately respond to a request for comment.

The sanctions were issued under a 2018 U.S. executive order that restored sanctions targeting Iran's oil, banking, and transportation sectors.

The Treasury Department issued a general license authorizing limited transactions with the sanctioned vessels under a "wind-down" period through June 29, a document on its website showed.