North Korea had an estimated 2.6 million modern slaves in 2016, according to the 2018 Global Slavery Index by the Walk Free Foundation, a global organization combatting modern slavery.

Why it matters: That means that one in ten North Koreans are imprisoned by forced labor or marriage, and a majority of those are enslaved by the state, according to the report. Andrew Forrest, founder of the Walk Free Foundation, told Axios that he hopes President Trump will challenge Kim Jong-un on the issue. Forrest said that "nobody is better qualified that Donald Trump to persuade and inform the North Korean president to the reality" of modern day slavery.

Go deeper: The estimated 400,000 people caught in modern slavery in the U.S.