Washington (CNN) Secretary of State Mike Pompeo emphasized Friday that he is "still in charge" of the diplomatic team running negotiations with North Korea and made it clear that he plans to continue serving in that capacity despite a blistering rebuke by Pyongyang earlier this week that called for the top US diplomat to be removed from denuclearization talks.

Pompeo also sought to downplay concerns about how the current impasse between Washington and Pyongyang over sanctions relief might impact talks going forward, a disagreement that contributed to President Donald Trump's decision to walk away from February's summit with Kim in Hanoi, Vietnam, without a deal.

"President Trump is obviously in charge of the overall effort but it will be my team, special representative {Stephen} Biegun will continue to lead the efforts to achieve what Chairman Kim committed to do back in June of last year which was to denuclearize," Pompeo told reporters at the State Department, standing alongside acting Defense Secretary Patrick Shanahan and their Japanese counterparts.

"As I have said before he has made that commitment to President Trump multiple times, he has made it to me personally a half a dozen times. I'm convinced we still have a real opportunity to achieve that outcome and our diplomatic team will continue to remain in the lead," he added.

Pompeo's comments come after North Korean Foreign Ministry official Kwon Jong Gun slammed the US Secretary of State for "letting loose reckless remarks and sophism of all kinds," specifically taking issue with his characterization of Kim Jong Un's recent speech to the country's rubber stamp parliament.

"Everyone has a clear interpretation of his speech which says that the US should change its way of calculation and come up with responsive measures before the end of this year," Kwon said, accusing Pompeo of misconstruing Kim's words for an unknown ulterior motive.

"Even in the case of possible resumption of the dialogue with the US, I wish our dialogue counterpart would be not Pompeo but another person who is more careful and mature in communicating with us," Kwon added.

Pompeo seemed to brush off that criticism Friday and indicated that the comments would have no impact on the prospect of negotiations going forward or his personal role in the process.

Isolating Trump

There has been little contact between the US and North Koreans since Hanoi and the Trump administration has not budged on its refusal to lift any sanctions until Pyongyang provides greater evidence that it is prepared to reduce its nuclear arsenal.

That disagreement is believed to be the primary reason the most recent round of talks between Kim and Trump fell apart in Hanoi.

However, Pompeo has publicly insisted that the US remains willing to return to the table and bluntly answered "yes" Friday when asked if he thinks talks with North Korea can continue without the US providing sanctions relief, despite Kwon's comments to the contrary.

Pyongyang immediately blamed Pompeo and national security adviser John Bolton for derailing the summit, a theme Kwon continued to push on Thursday, saying it "gives us a lesson that whenever Pompeo pokes his nose in, the talks go wrong without any results."

Pompeo was one of the primary drivers in Washington of those talks, and the historic first summit between Trump and Kim in Singapore, but the shine appears to have worn off the relationship.

Since Hanoi, North Korea has sought to not only portray Pompeo as an obstacle to diplomatic progress but as someone who actively working to prevent the two sides from reaching a deal despite Trump's eagerness to keep the momentum alive with Kim since Hanoi.

"North Korea thinks Pompeo and Bolton have a different opinion as to what a deal should look like and still believes that Trump remains the key to getting what they want," a diplomatic source familiar with the negotiation process said.

This source noted that recent criticism levied against US officials has not mentioned Trump himself, which is believed to be part of an effort by the North Koreans to isolate the President from his top advisers.

Eric Brewer, a former director for counterproliferation at the NSC under the Trump administration, said he also thinks the comments about Pompeo are normal bluster from North Korea, noting that we've seen Kim trying to drive a wedge between Trump and his advisers before.

However, he added that "it would be nice to see the President come out" and publicly endorse" Pompeo and Biegun.

Private frustrations

Pompeo went on to say Friday that the "mission set remains the same" with regards to North Korea as they work toward and completely verifiable and irreversible denuclearization.

But despite Pompeo publicly keeping his cool, his negotiators, including Biegun, are growing more and more frustrated behind the scenes, according to multiple sources familiar with their thinking.

Specifically, Biegun's frustrations are rooted in the lack of communication between the US and North Korea, according to multiple sources who have talked to him recently, noting that he has made it clear that he would like to get back to the table with his North Korean counterparts soon.

But that timetable remains unclear. Sources told CNN that South Korean President Moon Jae-in has a message from Trump that he has been asked to relay to Kim.

The message includes "things that matter to the current course of action, things that have to lead to something positive for the US-DPRK summit," a source said. "I believe he (Kim) would be very, very curious about what my President (Moon) would have to say after his meeting with the Trump administration."

While Moon has cast himself as the intermediary charged with jump starting talks between the US and North Korea, sources familiar with the situation have told CNN that there have not been any serious inter-Korean talks since Hanoi.

Both US and South Korean officials say that their leaders want another summit with Kim but it remains unclear when either meeting might take place.

Kim's next move

For his part, Kim is still weighing options that include taking provocative measures, such as a satellite launch, in an attempt to regain leverage by raising tensions with the US or go the other way: attempt to resume diplomacy while continuing to seek sanctions relief, a source told CNN earlier this month.

Pyongyang claimed it had conducted a "new tactical guided weapons firing test" on Wednesday but US officials have characterized the development as consistent with a low-level provocation and opted against condemning the move publicly.

Plans are also in the works for Kim to visit Russian President Vladimir Putin later this month. South Koreans say they are not worried, but that visit could further complicate the diplomacy between the US, North Korea and South Korea.

While some still fear that Russia will throw a wrench in the US-North Korean diplomacy, US officials do not see the meeting as much of a threat given that Russia has little leverage. There are hopes, among some US officials, that after North Korea holds meetings in Russia that they will come back to the table with the US.

On Thursday, Kim said he seeks to "closely cooperate" with Putin "as required by the new era." It appeared that he was making a point to the Americans.

Biegun held meetings in Moscow earlier this week ahead of Kim's planned arrival.

During those meetings, according to a Russian official, Biegun made it clear that the Trump administration does not want to go down the path of a step by step process with North Korea. Russia is not expected to push North Korea to bite at a big deal, they are content with that status quo, the official explained, given that they are getting involved.

"Maybe this is far as we can get," said the official, with little sense of urgency, explaining that the current halt to nuclear and missile testing from North Korea may be the ceiling on progress. The official also said that Russia didn't plan to torpedo the US talks, but rather hopes they could help get the two sides back to conversing.