"These individuals are important actors within North Korea's proliferation network who have been working to gain access to international markets," Under Secretary for Terrorism and Financial Intelligence, David S Cohen told reporters in Washington.
"We will continue to work with our partners around the world to expose these operations and hold North Korea accountable for its provocative and destabilising acts," he said.
The Treasury Department alleged that TCB acts as the financial arm of KOMID, Pyongyang's premier arms dealer and main exporter of goods and equipment related to ballistic missiles and conventional weapons.
KOMID has offices in multiple countries around the world and facilitates weapons sales for the North Korean government.
TCB plays a role in financing KOMID's sales of ballistic missiles and has also been involved in ballistic missile transactions from KOMID to Iran's Shahid Hemmat Industrial Group (SHIG), the US and UN-sanctioned Iranian organisation responsible for developing liquid-fueled ballistic missiles, the Department said.