What little is known about the man North Korean leader Kim Jong Un has tapped to prepare his summit with U.S. President Donald Trump suggests he’s more familiar with defending Pyongyang’s nuclear arsenal than giving it up.

Kim Hyok Chol, a career diplomat from an elite North Korean family, made his international debut just a few weeks ago as Pyongyang’s new point man for nuclear negotiations. In the run-up to the Feb. 27-28 summit, he has been in talks with U.S. counterpart Stephen Biegun to lay the groundwork for the meeting, taking diplomats by surprise.

To those who know him, Kim Hyok Chol is a skilled rhetorician who has played a crucial role in crafting the joint statement signed by the North Korean leader Kim and South Korean President Moon Jae-in at their latest summit last year. He also has a connection with Kim Jong Un, serving on the State Affairs Commission, the most powerful governing group chaired by the North Korean leader.

But his appointment left a few people flipping through their files of cadres to find out more. Channel A News, a South Korean TV outlet, drew a circle around him in a video from a White House meeting between Trump and North Korean officials in January, asking who he was.

Kim Hyok Chol was far from the center of attention. Dan Scavino, the White House’s social media director, sent out a tweet of the meeting that mentioned Pyongyang’s top envoy Kim Yong Chol but made no note of Kim Hyok Chol, who’s seen in a photo sitting slightly apart from rest of the North Korean contingent between two flags.

One of the few people familiar with Kim Hyok Chol outside of North Korea is Thae Yong Ho, a former North Korean diplomat who defected to South Korea in 2016, who describes him as an expert on nuclear deterrence, not denuclearization.

“At a very young age, Kim Hyok Chol was placed on the task force that wrote the drafts for North Korea’s nuclear strategy documents at its Foreign Ministry,” Thae told reporters at a news conference in Seoul on Tuesday.

Amid questions about Kim Hyok Chol’s role, one thing is certain — he reports to Kim Jong Un.

Kim Hyok Chol has been in the room for previous international nuclear negotiations, including the six-party talks a decade ago and is well-versed in the details of the deals, said Kim Hyun-wook, a professor at the Korean National Diplomatic Academy, who researches North Korea’s leadership.

“He also knows what North Korea would be willing to give and not — such as revealing the amount of nuclear material, nuclear weapons and missile trajectories,” Kim Hyun-wook said in an interview.

Kim Hyok Chol became North Korea’s ambassador to Spain from 2015. Two years later, Madrid expelled him in retaliation for North Korean nuclear and missile tests. He has also ventured where few North Korean diplomats go — social media, appearing in videos posted to YouTube calling for the U.S. to drop sanctions choking North Korea’s economy.

He gave a 2015 interview with Elcano Royal Institute, a Spanish think tank, saying North Korea has sought to remove nuclear weapons from the entire Korean Peninsula for decades but was forced to build its own nuclear arsenal to prevent a U.S. attack.

“I hope U.S. in the future acknowledges that these sanctions on my country is useless and change their policies,” he said in the interview conducted in English and posted on YouTube.

Born and raised in a diplomat’s household, Kim Hyok Chol studied French at the Pyongyang University of Foreign Studies and took a desk job at the Foreign Ministry, according to the defector Thae. He was mentored by Ri Yong Ho, who is now foreign minister, according to Thae.

Thae said Kim Hyok Chol is meticulous about the wording of North Korean statements, and that was on display in Beijing in 2005 for nuclear talks.

“At the six-party talks, when each representative was given only two minutes to talk, he was really good at scripting what exactly needed to be delivered within those two minutes, which is probably why he’s now in Hanoi,” Thae said in an interview.

But as early as January, it was North Korean Vice Foreign Minister Choe Son Hui having discussions with Biegun when they met on the sidelines of a conference in Stockholm. The secretive North Korean regime hasn’t said why she’s no longer is negotiating with Biegun.

Whether it’s Choe or Kim Hyok Chol, the master tactician in North Korea’s nuclear diplomacy, Kim Kye Gwan, is still pulling a few strings after being at the forefront of the state’s international atomic dealings since the mid-1990s, according to South Korea’s former top envoy to international nuclear talks, Chun Yungwoo.

“Kim Kye Gwan is behind these negotiators,” said Chun, adding that an aging tactician may no longer be up to the physical challenge of face-to-face talks.

Chun also said that no matter who’s at the table, North Korea will be well-prepared for the summit.

“They are very good at achieving their objectives. They are very smart people. They know how to outmaneuver the Westerners, the Americans, the Chinese, everybody,” he said.