What happened last month at the North Korean Embassy in Spain?

Spanish authorities have confirmed they are investigating a reported attack on the North Korean Embassy in Madrid, a spokesperson for Spain’s National Police told CNN.

The alleged incident, which was reported to have taken place on February 22, was carried out by 10 people carrying fake firearms who entered the compound and interrogated and beat up people inside, according to the Spanish newspaper El País.

Spanish media reports say the assailants restrained staff members with rope and stole a variety of items before fleeing in luxury vehicles.

During the attack, a Korean woman managed to escape from the embassy and her screams alerted residents, who called the police, the newspaper said. When police officers tried to knock on the door, they were told nothing was going on.

The alleged attack occurred days before US President Donald Trump and North Korean leader Kim Jong Un held their second summit, in the Vietnamese capital of Hanoi.

Trump and Kim’s meeting ended abruptly in part due to disagreement over when to remove UN sanctions in exchange for steps toward Pyongyang’s denuclearization. But Trump and his aides said both sides left on good terms.

Police declined to disclose details about the embassy case, as the matter is under investigation, and Spain’s Interior Ministry said it does not comment on active investigations. CNN has reached out to Spain’s Foreign Ministry comment.

A source from the US government said it’s believed that the Cheollima Civil Defense, a shadowy North Korean dissident group, is behind the attack.

The Washington Post was first to report the involvement of the CCD the secretive group, whose goal is to overthrow the Kim regime. The group did not respond to CNN’s request for comment and has not publicly claimed responsibility for the attack.

The Cheollima Civil Defense first gained international recognition after it reportedly came to the defense of Kim Han Sol, the son of Kim Jong Nam. Kim Jong Nam, the elder half-brother of North Korea’s leader, was exposed to the deadly nerve agent VX in 2017 while entering an airport in Kuala Lumpur, killing him in minutes. US, South Korean and Malaysian authorities have pinned the attack on Pyongyang, but North Korea has adamantly denied any responsibility.

It’s unclear why Kim Jong Nam was killed, but analysts said that if North Korea was behind the murder, perhaps Kim Jong Un saw his brother and his family as a possible threat to his leadership.

“The Cheollima Civil Defense established credibility by acting quickly and getting Kim Han Sol, the son of Kim Jong Nam, within days of his father’s gruesome assassination,” said Sung-Yoon Lee, a professor at Tufts University Fletcher School of Law and Diplomacy.

Connection to Kim Hyok Chol?

Spanish media quoted anonymous sources speculating that the embassy incident may be connected to former North Korean Ambassador Kim Hyok Chol.

Kim Hyok Chol (right), the North Korean leading negotiations with the United States, arrives in Hanoi on February 20.

Kim, who now serves as one of the top negotiators in talks with the United States, previously was Pyongyang’s envoy to Spain. He was expelled in 2017 in response to North Korea’s successive missile and nuclear tests.

Lee said that if the Cheollima Civil Defense was behind the attack, it would have had strong incentives to secure intelligence on Kim Hyok Chol, “if only to enhance its own stature.”