Cheollima Civil Defence is believed to be the first organised opposition to the dynasty that has ruled North Korea for more than seven decades.

What little is known about the secretive group is based on its own public statements and Spanish court documents detailing its audacious raid on the North Korean embassy in Madrid in late February.

The group’s use of direct action contrasts with other movements, which have traditionally used propaganda, sent inside the country via leaflets and USB drives, to foment popular opposition to Kim Jong-un’s regime.

The organisation, which also calls itself Free Joseon, entered the public consciousness in 2017 when it claimed it had protected the son of Kim Jong-nam – the half brother of the North Korea’s leader – after Kim was assassinated, allegedly with Pyongyang’s involvement, at Kuala Lumpur airport in February 2017.

On 1 March the group published a statement declaring itself the North Korean provisional government in exile and vowing to overthrow the regime for committing crimes against humanity.

It claimed to be “preparing the foundations for a future nation built upon respect for principles of human rights and humanitarianism, holding sacred a manifest dignity for every woman, man, and child”.

It added: “We indict this immoral and illegitimate regime for the devastating starvation of millions, despite the ability to feed them; for government-sponsored murder, torture, and imprisonment; for overwhelming surveillance and thought-control.”

The group called on the North Korean diaspora to help establish a “new Joseon” – a reference to a Korean dynastic kingdom whose name North Koreans still use to refer to the peninsula.

Adrian Hong Chang, who was named by a Spanish court as the ringleader in the embassy raid, is a longtime activist who co-founded the refugee aid organisation Liberty in North Korea, according to NK News.

Under the name Adrian Hong he has written opinion pieces about the regime for US publications.

In an opinion piece for Foreign Policy magazine after the death of Kim Jong-il in December 2011, he wrote: “This much is clear: North Korea will fall. It is simply a question of when and how. But it is far better to have a coordinated, controlled landing, at the time of one’s choosing, instead of waiting for the worst to happen at any moment. And a reunified, free Korea can be a powerful force for good in the world, and a potent economic engine.”

This month, Cheollima, which means pegasus, posted a video purporting to show a North Korean smashing portraits of Kim Jong-il and his father, the regime’s founder, Kim Il-sung. The video’s title, In Our Homeland, suggested the footage was taken during the group’s raid on the North Korean embassy in Madrid.

In its statement claiming responsibility for the raid, the group criticised the role North Korean diplomats play in supporting “a giant criminal enterprise”.

“Embassies around the world run by the current Pyongyang regime are not like the traditional diplomatic, commercial and cultural outposts of legitimate governments that serve their nation’s interests and respect international norms,” it said.

“The regime’s embassies and offices are hubs of illicit narcotics and arms trafficking, mediums for the furtherance of propaganda of a totalitarian regime that systematically commit crimes against humanity against its own (and others) without current parallel.

“They are launch pads for global cyber attacks and thefts, assassinations, kidnappings, and hostage taking – including of the families of their own diplomats. This charade of pretending that the regime is a normal government must stop – the regime is simply a giant criminal enterprise.”