The US treasury named the two men as Kim Jong-sik and Ri Pyong-chol, and said both were “key leaders” of North Korea’s ballistic missile programme.
The UN Security Council imposed new sanctions on North Korea on Friday in response to ballistic missile tests.
North Korea said the move was “an act of war” and tantamount to a total economic blockade.
The new US sanctions will block any transactions by the two men carried out in the US, essentially freezing any American assets they may have.
Both men are regularly photographed alongside North Korean leader Kim Jong-un at missile launches.
In the past year, the country has tested ever more ambitious types of missile, and says it can now reach the entire continental United States.