JON WOLFSTHAL: He had a tremendous reserve of energy both in frustrating times during the Obama administration when we couldn't get any traction with North Koreans and, I think, during the Trump administration where it's been frustrating just with the internal dynamics.
Kang was addressing the UN Human Rights Council a day after the Olympic Winter Games closed in her country.
The newspaper also accused the USA of misleading the worldwide community by saying the North is begging for talks because it is giving in to sanctions and pressure.
Joseph Yun's resignation sparked rumors of policy differences with the Trump administration.
Asked whether there would be any consequences for Russia's action, Sanders replied: "I'm not going to weigh in ahead of time and we certainly have never broadcast what we might do, but it's something the president does take very seriously".
Another hostile step by the North, such as conducting another intercontinental ballistic missile test, would increase the chances of a United States military response.
As a precondition for bilateral talks, Research Professor James Przystup at the National Defense University suggests Pyongyang has to declare a moratorium on missile and nuclear tests, commit to denuclearization and implementation of the 1991 South-North Agreement on Reconciliation, Non-Aggression and Exchange.
According to Kyung-wha, sanctions are not an end in themselves and not meant to bring down North Korea.
"This is exceptionally bad news", Frank Jannuzi, an East Asia expert who heads the Mansfield Foundation, said on Twitter."Joe Yun is the only senior official left at State who has experience dealing with the complexities of North Korea policy".
Trump announced on Friday what he called the "largest ever" set of sanctions against North Korea and threatened a "phase two" if the measures aren't effective.
South Korea's foreign ministry said it had been aware Yun planned to step down and that it had highly appreciated his work.
Over the weekend, North Korean indicated in a meeting with South Koreans that they are ready for talks with the U.S. This can be seen to suggest that North Korea has been driven into a corner by trade restrictions as a result of the sanctions.
But no sooner had the North and the United States declared their willingness to talk to each other - something they have in fact done before - than it became clear that the two sides remained stubbornly far apart. "But something has to be done".
The special envoy's authority to engage with North Korea appeared to be undercut by a tug-of-war between the White House and State Department over North Korea policy under Trump. Though he has said he will stay on until a replacement is named, five of the six undersecretary posts - the department's third-highest-ranking positions - now need to be filled.