"Having a missile test is not the way to sit down with the president because he's absolutely not going to do it," Haley said when asked about conditions for President Donald Trump's meeting with the North's leader. "I can tell you, he can sit there and say all the conditions he wants. Until he meets our conditions, we're not sitting down with him."

Early this month, Trump said he would be "honored" to meet with Kim "under the right circumstances."

On Saturday, Choe Son-hui, director-general of the North American affairs bureau at the North's Foreign Ministry, also told reporters that Pyongyang is willing to hold talks with the US "under the right conditions."

Choe spoke in Beijing on her way back to Pyongyang after holding talks in Oslo with a group of American experts, headed by Suzanne DiMaggio, director of the US think tank New America. The US team also included Thomas Pickering, former US envoy to the UN, and Robert Einhorn, the US State Department's former special adviser for nonproliferation and arms control.

Haley said that the US is prepared to seek tougher sanctions on Pyongyang.

"There's a lot of sanctions left that we can start to do, whether it's with oil, whether it's with energy, whether it's with their maritime ships, exports. We can do a lot of different things that we haven't done yet. So our options are there," she said.

The envoy also said China has been cooperative in US efforts to tighten the screws on the North.

"I can tell you we're working better with China than we ever have," Haley said. "We're determined to take care of South Korea, which is why we have our mission there, working on that as well. And then we're going to continue to take care of Japan." (Yonhap)