The United States and China made progress Tuesday toward a draft UN sanctions resolution to punish North Korea for its recent nuclear tests and push it to the negotiating table.

After talks in Washington, China's Foreign Minister Wang Yi and US Secretary of State John Kerry said the draft was still being "evaluated" by officials before being submitted to the UN Security Council.

But both powers vowed that they would not accept a nuclear-armed North Korea and expressed confidence the resolution would be strong enough to force Kim Jong-Un's isolated regime to reconsider its strategy.

China wants its neighbor to halt its weapons program -- most recently shown by the January 6 test of an atomic bomb Pyongyang claims was a new thermonuclear device -- and return to six-party international talks.

But Beijing has been more cautious than Washington in its approach, fearing that too severe a response could trigger the collapse of the pariah regime and a political and humanitarian crisis on its border.

Nevertheless, Wang said his talks with Kerry had made progress in agreeing on a draft sanctions resolution to be presented to the full UN Security Council.

"We do not accept the DPRK's nuclear missile program and we do not recognize the DPRK as a nuclear weapons state," he said, using the abbreviation for North Korea's official name.

"Important progress has been made in the consultations and we are looking at the possibility of reaching agreement on a draft resolution and passing it in the near future."

Both men said the goal of the resolution is not to worsen the standoff with Kim Jong-un's isolated regime, but to persuade it to resume talks on ending his nuclear program.

"We have made significant progress, it has been very constructive in the last days," Kerry said.

"And there is no question that if the resolution is approved, it will go beyond anything that we have previously passed," he added.

"I believe that what we are considering is significant but, as I say, it is in the appropriate evaluative stages and we both hope that this can move forward very soon."

- Peace treaty explored -

Pyongyang has done nothing to moderate its tone since January's test caused international outrage, and on Tuesday promised a "strategic" response if it felt threatened by an upcoming joint US-South Korean military exercise.

Kerry said a denuclearized North Korea could one day enter talks with Washington to negotiate a formal peace deal to officially end the hostilities that began with the outbreak of the Korean War in 1950.

On Sunday, the State Department had confirmed that Pyongyang had reached out to the United States in a tentative bid to discuss a peace treaty, but added that the January test had derailed the initiative.

"We carefully considered their proposal, and made clear that denuclearization had to be part of any such discussion. The North rejected our response," spokesman John Kirby told reporters.

Kerry also said that there would be no need for the United States to deploy its THAAD missile defense system in its ally South Korea, as planned, if the North's weapons were not threatening the region.

China has expressed concern that sending he system to South Korea could upset regional power balances and strain its ties with Seoul, despite US insistence it would be aimed at countering Pyongyang.