The United States is using sanctions to get North Korea to realize that the impoverished communist nation cannot rebuild its broken economy while holding onto nuclear weapons, a senior American diplomat said Wednesday.

"The goal of pressure isn't punishment," Assistant Secretary of State Daniel Russel said during a seminar on Korea. "It's to bring North Korea's leadership to the realization that their hope of getting the world to accept them as a nuclear power and also provide them with economic assistance isn't working and that it won't work."

Russel was referring to the North's "byeongjin" policy of pursuing nuclear weapons and economic development at the same time.

South Korea and the U.S. have said the policy is a nonstarter, but some experts have cautiously said in recent months that the policy might be working, citing signs of improvement in the North's economy.

Russel stressed that the U.S. is open to dialogue with Pyongyang, but the regime has shown no signs of readiness to negotiate away its nuclear programs.

"We're not refusing. North Korea is refusing to talk," he said.

"It is in fact an unfortunate reality that North Korea's nuclear and missile program continue in gross violation of international law and of its own solemn commitments and obligations," he said.

The U.S. and South Korea have gone the extra mile to reach out and probe the North's willingness to engage, Russel said, emphasizing Pyongyang must at least honor its denuclearization commitment in order for negotiations to have any chance of success.

"These can't be phony talks," he said. "The North has to accept real negotiations."

Russel described the current U.S. handling of the North Korean nuclear issue as a "treatment," rather than a "cure," saying a cure lies only in "bonafide negotiations."

Key elements of the "treatment" include deterrence, pressure and diplomacy, he said.

Russel said some of the "toughest sanctions in history" have been imposed on the North.

But some participants in the seminar, co-sponsored by the Korea Foundation and the Center for Strategic and International Studies, called for more biting sanctions.

Chun Yung-woo, a former South Korean national security adviser, said that there are signs of North Korean leader Kim Jong-un making progress in his "byeongjin" policy of seeking nuclear and economic development.

"What concerns me is he's making progress," Chun said. "I think he may be making progress because of weak sanctions ... the sanctions which really do not bite North Korea."

Former Assistant Secretary of State Kurt Campbell also said sanctions against the North are much weaker than those against Iran and Myanmar.

"It is commonly felt and viewed that North Korea is one of the heaviest sanctioned countries in the world and it's just not true.

It's just not accurate," he said. "We had many times more sanctions against Myanmar, many times more, and also against Iran and we've tried many more creative techniques." (Yonhap)