North Korean leader Kim Jong-un arrived at Singapore on Sunday, June 10, for a much-anticipated summit with U.S. President Donald Trump.

Running alongside his Mercedes-Benz limousine as it traveled to the St. Regis Hotel were his entourage of bodyguards.

We saw them at the #InterKoreanSummit. North Korea's men in black are once again running alongside the vehicle carrying Kim Jong Un as it heads to the office of Singapore's Prime Minister @leehsienloong #TrumpKimSummit #tictocnews pic.twitter.com/xPpaL8ddXN

— Bloomberg QuickTake (@QuickTake) June 11, 2018

This was their second time appearing in front of the international media.

They first captured the world's attention back in April when they escorted Kim to the historic inter-Korea summit with South Korean President Moon Jae In.

But they are more than just a show, they are responsible for their Supreme Leader's safety.

In case you wanted to know, here is some information about the North Korean leader's running bodyguards.

Must be around same height as Kim

According to AFP, the 12-man unit -- dressed immaculately in suits and matching blue and white striped ties -- are part of something called Central Party Office #6, or formally known as the Main Office of Adjutants.

They form the immediate line around Kim and are selected from Korean People's Army (KPA) recruits.

The selection criteria include fitness, marksmanship, martial arts skills and even looks.

According to the BBC, they need to be around the same height as Kim, and must not have any visual impairments.

Only state leader with this kind of security structure

After passing a strict background investigation -- which goes back two generations in the bodyguard's family -- they are subjected to an intensive training programme.

The running bodyguards are the only ones in North Korea who are allowed to carry loaded firearms next to Kim.

But although they are armed, the bodyguards mainly protect Kim by their skills of observation -- watching out for people near the leader and the premises.

The second and third lines of security around Kim comprise of the Guard Command (GC), who secure the physical premises of wherever Kim happens to be, whether he's within or outside North Korea.

Kim is the only state leader with this sort of three-tier personal security structure (although he has fewer bodyguards as compared to his late father).

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Kim's extremely concerned about his security

Security is a major concern for Kim. He was reportedly afraid of assassination attempts while in Singapore.

His trip to the city-state is the furthest he has traveled as leader of North Korea.

Other than the three airplanes and a convoy of armoured vehicles he brought with him from Pyongyang, he reportedly brought his own toilet as well -- a precaution he takes to prevent "determined sewer divers" from getting "insights" into his stools.

However, with the S$20 million Singapore has spent to secure the summit, he should be able to rest easy.

Top image via Twitter