The United States will use "the full range of tools" to make North Korea realize that it can't achieve the security and prosperity it seeks as long as it sticks to nuclear weapons, Washington's chief negotiator with Pyongyang said Tuesday.

Amb. Sung Kim, special representative for North Korea policy, made the remark during a Senate Foreign Relations Committee hearing, rejecting criticism that the U.S. is not doing enough to get Pyongyang to give up its nuclear program.

"Holding North Korea responsible for its own choices does not mean just waiting and hoping the regime will one day come to its senses," Kim said. "We are committed to using the full range of tools -- deterrence, diplomacy, and pressure -- to make clear that North Korea will not achieve security or prosperity while it pursues nuclear weapons, abuses its own people, and flouts its longstanding obligations and commitments."

The envoy also said that the North's bad behavior has earned no benefits from the U.S.

"Instead, we have tightened sanctions and consistently underscored to the DPRK that the path to a brighter future for North Korea begins with authentic and credible negotiations that produce concrete denuclearization steps," Kim said.

The envoy said the U.S. stands ready to defend its interest and its allies from the North Korean threat and have made it a priority to strengthen and modernize the alliances with South Korea and Japan. Last week's summit between President Park Geun-hye and President Barack Obama strengthened the alliance, he said.

Kim said the U.S. has also sustained pressure on the North to "increase the costs" of its destructive policy choices. He cited an executive order that Obama issued in January to impose fresh sanctions on Pyongyang in the wake of the regime's hacking of Sony Pictures.

He stressed that sanctions enforcement has improved over the past two to three years, causing some pain in the North. He added that revenues from North Korea's illicit activities overseas have gone down as a result.

"Our financial sanctions are always more effective when supported by our partners, and so we've also focused on strengthening multilateral sanctions against North Korea," he said.

"We will continue to press for robust implementation of U.N. sanctions and enhanced vigilance against the DPRK's proliferation activities worldwide."

As important as sanctions is the North's political isolation, Kim said.

The envoy said that the U.S. is maintaining close coordination with members of the six-party talks to ensure that "wherever Pyongyang turns, it hears a strong, unwavering message that it must live up to its international obligations, and that the path to a brighter future begins with credible negotiations and concrete denuclearization steps."

Kim also said the U.S. is interested in holding a five-party meeting, excluding North Korea.

"It's something that we've been very interested in pursuing. I think it would make a lot of sense for us to have a five-party gathering in which all five of us at one time share notes and try to come up with a common strategy," he said.

"I do think it would be useful for us try to organize a five-party gathering to coordinate our efforts. Some of the parties have been cautious about the signal that a five-party gathering would send. But I believe that it would be quite useful," he said, adding that China and Russia have been cautious.

Meanwhile, Amb. Robert King, special envoy for human rights in the North, said during the hearing that radio broadcasts into the North are one of the most effective tools in spreading outside information to the totalitarian nation.

Radio broadcasts are "important in breaking down the information barriers that the DPRK government has imposed on its people," he said, adding, "Because of government policies, radio remains the most important means to get information into the DPRK." (Yonhap)