WASHINGTON (Yonhap) ― U.N. sanctions on North Korea are working as they are diminishing Pyongyang’s profits from illicit activities, and the U.S. will continue to tighten the screws on the communist nation, Washington’s pointman on the North said Wednesday.

Glyn Davies, special representative for North Korea policy, also said during a hearing of the House Foreign Affairs Committee’s Asia-Pacific subcommittee that Pyongyang won’t give up its nuclear program unless the U.S. keeps pressure on the regime.

“It is clear that U.N. sanctions are having an effect and are diminishing North Korea’s ability to profit from its illicit activities,” Davies said. “The United States will continue to take steps to strengthen and bolster the existing sanctions regime, both through work in the U.N. context and through our own national measures.”

Over the past two years, the U.S. has substantially upped the cost of North Korea’s illicit activities to reduce resources earned through weapons exports that are subsequently reinvested in the weapons of mass destruction program, Davies said.

A particular focus has been on implementing U.N. sanctions targeting illicit activities of the North’s diplomatic personnel and cash couriers, its banking relationships, and its procurement of dual-use items for its WMD and missile programs, he said.

Also Wednesday, the U.S. Treasury Department imposed sanctions on two North Korea shipping firms after a cargo ship from the communist nation was caught transporting missiles and other items from Cuba last year in violation of U.N. resolutions.

The Treasury said that Chongchongang Shipping Co. is the operator of the once-seized freighter Chong Chon Gang, and Ocean Maritime Management Co. played a key role in having the ship’s crew lie about the cargo and providing false documents to Panamanian authorities.

The North Korean freighter was seized by Panama in July 2013 while carrying Soviet-era MiG-21 fighter aircraft, surface-to-air missiles and other arms-related material hidden under sacks of sugar.

Davies said that the U.S. has tried to cut off the inputs to the North’s weapons program through sanctions and interdiction, adding that Panama’s seizure of the North Korean cargo was an “indicator that the rest of the world gets the message.”

He also stressed that the U.S. policy on North Korea is “strategic impatience,” rejecting the widely used characterization of the administration of President Barack Obama’s policy on Pyongyang as “strategic patience.”

Davies said the North is “increasingly a global outlier in every sense” as the regime continues to pursue nuclear weapons and ballistic missiles, and poses threats to the U.S. and its allies while starving its people and violating their rights.

“We have no illusions about the nature of the regime, nor its intentions. We have refused to respond to DPRK provocations with concessions. North Korean has obtained no benefits from its bad behavior. Instead, we have tightened sanctions,” Davies said.

“As we seek the negotiated complete, verifiable, and irreversible denuclearization of North Korea, we know we must keep pressure on Pyongyang or it will not give up the weapons it claims it needs. That is why our policy mix includes sanctions and traditional deterrence measures,” he said.

The six-party talks on ending the North’s nuclear program have been stalled since the last session in late 2008. North Korea has said it wants an unconditional resumption of the talks, but Seoul and Washington have demanded Pyongyang first take concrete steps demonstrating its denuclearization commitment.

“The DPRK says it is ready for ‘talks without preconditions.’ No codebook is needed to decipher North Korea’s intention: seek open-ended discussion that diverts attention away from its nuclear program and to avoid committing to denuclearization,” Davies said.

“Pyongyang has been explicit on this point: it seeks acceptance as a nuclear weapons state. It wants to use six-party talks ... as cover to continue its clandestine weapons development. We are not interested in six-party talks that do not focus directly on steps to implement” the North’s denuclearization promise, he said.

He said that North Korea’s actions signal that it has no interest in denuclearizing.

Davies said that the U.S. and China agree on what the North needs to do, and Washington is now focusing on coming to agreement with Beijing on the “how” and the “when” of denuclearization.

“Can China do more to exercise its unique levers of influence over Pyongyang? Of course. And we remain in close touch with Beijing about ways we can work together to bring the DPRK to the realization that it has no other viable choice but to denuclearize,” he said.