The United States is imposing more sanctions on Iran and taking steps to stop Iran from using front companies and banks to evade sanctions.

Undersecretary of the Treasury for Terrorism David Cohen says the United States will keep ratcheting up the pressure on Iran as long as it refuses to address the global concern about its alleged nuclear weapons program.

Thursday's actions target 11 Iranian entities and four individuals the Treasury Department calls part of a government-backed network of weapons proliferators.

U.S. authorities also are exposing the names of numerous front companies that the Iranian government set up to avoid sanctions on oil sales.

The new sanctions freeze relevant Iranian assets in the United States and ban U.S. citizens from doing any business with the Iranian companies.