Kim Jong Un's elite bodyguards run beside his car because of a Clint Eastwood movie

Kim Kyung-Hoon/REUTERS

Bodyguards of North Korean leader Kim Jong Un wait for his arrival at Dong Dang railway station in Vietnam, March 2, 2019.

• Kim Jong Un's bodyguards sparked international attention after they were seen running beside his car at a summit in Singapore last year.
• The elite force is chosen from among North Korea's most loyal political families, a new book reports.
• President Donald Trump made a historic visit to North Korea over the weekend.
• Visit Business Insider's homepage for more stories.

US President Donald Trump made a historic trip to North Korea on Monday, meeting North Korean leader Kim Jong Un on his home turf. The meeting offered a view of the secretive Hermit Kingdom - including a glimpse of the protection apparatus that ensures Kim's safety.

Kim's life is shrouded in mystery, and his bodyguards remain a source of endless fascination. During Kim's visit to Singapore last year for talks with the US, images of a dozen of Kim's bodyguards running alongside his car made headlines.

According to "The Great Successor: The Divinely Perfect Destiny of Brilliant Comrade Kim Jong Un" by Washington Post correspondent Anna Fifield, "Kim got the idea for this human shield from Clint Eastwood."

REUTERS/ Stringer

North Korean bodyguards run along a limousine transporting North Korea's leader Kim Jong Un upon his arrival at the border town with China in Dong Dang, Vietnam, February 26, 2019.

"As a boy, he's seen the movie 'In the Line of Fire,' in which Eastwood plays a US Secret Service agent who had been guarding John F. Kennedy when he was assassinated in 1963. Eastwood's character and other agents run alongside the president's car," Fifield's book explains.

Becoming a bodyguard for the North Korean leader is extremely difficult - according to Lee Yeong Guk, a bodyguard for Kim Jong Un's father deceased father Kim Jong Il, it's "harder than passing through the eye of a needle."

Potential recruits are chosen from the military, and must pass through several tests to judge their health, eyesight, looks, personality, and family background, according to Fifield. "Those charged with guarding the Brilliant Comrade [Kim Jong Un] must have excellent political credentials and come only from the most loyal classes." They must be around the same height as Kim, and they are among the only citizens allowed to carry firearms near the leader.

Shamil Zhumatov/Reuters

North Korean leader Kim Jong Un attends a wreath laying ceremony at a navy memorial in Vladivostok, Russia April 26, 2019.

Lee, the former bodyguard for Kim Jong Il, told ABC news in 2018 that guards "have to be good at shooting guns. Then Taekwondo, things like throwing knives, swimming, and marching, these are the first. And the second is serving Kim Jong Il with loyalty, that's also the third and the fourth."

The bodyguards come from the Main Office of Adjutants, or, more colloquially, Central Party Office number 6, according to the BBC. Although they're armed with handguns, they are primarily dependent on their observational skills and non-lethal methods - like their hands and bodies - to deal with threats.

The bodyguards are part of the larger Supreme Guard Command, an approximately 100,000-strong force that navigates a number of different security threats that Kim might face, according to TIME. North Korea takes extraordinary measures to protect Kim Jong Un, including taste-testing food before it's served to him and toting around his own personal toilet so no foreign government can analyze his DNA for health information.