There is a flurry of diplomatic activity ahead of a planned meeting between U.S. President Donald Trump and the leader of the Democratic People’s Republic of Korea Kim Jong Un. The White House said President Trump still hopes the historic summit will happen before the end of May. But many details are still being worked out behind closed doors. CGTN’s Roee Ruttenberg has the story.

As the DPRK Foreign Minister Ri Yong Ho was in Stockholm for surprise closed-door talks with Swedish officials, South Korea’s top diplomat was in Washington. Kang Kyung-wha’s visit comes just days after U.S. President Donald Trump accepted an offer to meet face-to-face with DPRK leader Kim Jong-un.

“We’re cautiously optimistic that the talks will happen and that this will be a breakthrough for a peaceful resolution of the North Korean nuclear issue,” Kang said.

Back in Seoul, officials said they were seeking high-level talks with Pyongyang this month ahead of their own summit with Kim set for April.

Im Jong-seok, the South Korean president’s chief of staff, said, “We’ve decided to narrow down the agenda topics to denuclearizing the Korean peninsula, securing permanent peace to ease military tension and new, bold ways to take inter-Korean relations forward.”

South Korea said President Moon Jae-in hopes to meet with Trump before the U.S. president’s historic summit with the North’s leader.

According to the White House, Trump and Moon spoke by phone on Friday, and, “agreed that concrete actions, not words, will be the key to achieving permanent denuclearization of the Korean Peninsula”.

Until then, Washington’s approach to Pyongyang would remain unchanged.

“We are continuing our maximum pressure campaign on North Korea,” explained White House Press Secretary Sarah Huckabee Sanders. “We are continuing to ask our allies to engage in that maximum pressure campaign, not to let up that point for any reason until we see real progress on the promises made by the North Koreans.”

The DPRK has yet to confirm the meeting. But Stockholm on Friday said Sweden may play a part.

“We are hoping that if we can use our role and also our contacts then we will put it to the best use. And then it’s for the parties to decide what is the way forward and the process from now on,” said Margot Wallstrom, the Swedish foreign minister.

Washington’s former envoy to the DPRK Joseph Yun – who quit last month – said he understood the resistance of some in the White House towards Pyongyang.

“They have been relentless in testing missiles, nuclear devices. So this is not easy,” he said. “It’s a complicated problem. But I know we’re getting a great start if we start off with a summit.”

Yun said the president has struggled to get his whole team on the same side.

That Donald Trump himself made the decision to accept the offer may help explain some of the rumblings heard in recent days. There are reports that Trump did not get along with his now-fired secretary of state, and that his national security adviser – who openly floated the idea of a pre-emptive strike on the DPRK – may be on his way out.

Jim Walsh on US and ROK’s diplomatic push for talks with the DPRK

For more on the Korean Peninsula diplomacy, CGTN’s Mike Walter spoke with an international security expert, Jim Walsh, from Boston.