The chairman of the U.S. Senate Foreign Relations Subcommittee on East Asia called for greater efforts to impose additional sanctions on North Korea as he welcomed the Treasury Department's recent designation of Pyongyang as a "primary money laundering concern."

The unprecedented designation, announced Wednesday, is considered one of the most powerful sanctions the U.S. has ever imposed on the communist nation, and is designed to cut off Pyongyang from the international banking system for pursuing nuclear and missile development.

The designation came as part of the North Korea Sanctions and Policy Enhancement Act (NKSPEA) enacted in February to punish the North for conducting its fourth nuclear test in January and a long-range rocket launch the following month in violation of U.N. resolutions.

"I'm pleased the Treasury Department, as required by my bill, acted to apply additional pressure to North Korea through this important designation that will send a strong message to Pyongyang and its enablers," Sen. Cory Gardner (R-CO), a key author of the sanctions legislation, said in a statement.

"I encourage Treasury to continue to vigorously pursue and implement additional sanctions outlined in my legislation, including designations against North Korea for cyberattacks and human rights violations," the senator said.

Gardner said he held a meeting in April with Acting Under Secretary for Terrorism and Financial Intelligence Adam Szubin, who is responsible for enforcing U.S. economic sanctions policy, to call for vigorous implementation of the sanctions law.

"I urged him to fully implement NKSPEA, and particularly with regard to entities outside of North Korea whose illicit actions enable the regime's survival," he said.

Gardner is one of a handful of leaders in Congress who have consistently called for greater attention to the North's nuclear and missile threats as well as its human rights abuses when the Obama administration has been preoccupied with other problems like Syria, Russia and the Islamic State group.

Taking a cue from his North Korea sanctions law, the U.N. Security Council adopted a resolution banning the North's exports of coal, iron and other mineral resources, a key source of hard currency that accounts for nearly half of the country's total exports.

Last week, Gardner also introduced an amendment to next year's defense budget bill that calls for the deployment of the Terminal High Altitude Area Defense (THAAD) missile defense system in South Korea so as to better defend against missile threats from the North. (Yonhap)