On Tuesday, the Treasury Department designated Korea Kwangson Banking Corp. (KKBC) as a proliferator of weapons of mass destruction (WMD). The firm provided financial services to two other companies known to participate in North Korea's WMD and missile programs.

KKBC is based in North Korea and has at least one overseas branch in China.

"North Korea's use of a little-known bank, KKBC, to mask the international financial business of sanctioned proliferators demonstrates the lengths to which the regime will go to continue its proliferation activities and the high risk that any business with North Korea may well be illicit," Under Secretary for Terrorism and Financial Intelligence Stuart Levey said in a statement.

The two other companies are Tanchon Commercial Bank (Tanchon) and Korea Hyoksin Trading Corporation (Hyoksin), a subordinate of the Korea Ryonbong General Corporation (Ryonbong).

The George W. Bush administration identified Tanchon and Ryonbong as weapons proliferators in 2005. The Treasury Department identified Hyoksin as a subsidiary of Ryonbong in June.

Treasury designated KKBC under an executive order that allows the department to freeze their assets and prohibit U.S. companies from engaging in business transactions with them.

The department said that since 2008, KKBC has assisted the three other companies in transferring funds to other munitions companies and arms dealers.