U.S. President Barack Obama says that the U.S. will impose additional sanctions on Iranian oil exporters.

The White House announced the sanctions in a statement on Tuesday, calling them part of the U.S.’s commitment to prevent Iran from acquiring nuclear weapons by raising the cost of Iran’s defiance of the international community. The additional sanctions will also affect some Chinese and Iraqi banks that make transactions with Iranian oil exporters.

Obama signed an executive order authorizing additional sanctions on Iran on July 30th.