North Korea’s national team played a match in Qatar earlier this month. That North Korea would agree to play such a match at the height of a diplomatic crisis shows just how strong diplomatic and economic ties are between Doha and Pyongyang.

Qatar’s support for terrorism has led to a blockade from five countries. Egypt, Saudi Arabia, Yemen, Bahrain have all severed ties. Other countries ranging from Jordan to Chad have all reduced diplomatic ties.

It’s not only groups like Hamas and the Taliban with which Qatar has ties. The country also has close relations with perhaps the world’s worst abuser of Human Rights: North Korea.

In recent years North Korean workers were essentially working as slaves in the world’s richest country per capita. The North Korean workers rushed to complete the countries ambitious infrastructure plans which include building the stadiums, housing, and hotels in Qatar that will one-day hold thousands of wealthy fans for the FIFA 2022 World Cup.

According to the 2016 State Department report on Trafficking in Persons, North Korean workers are sent around the world from the Russian Federation to China to earn hard currency for the hermit kingdom.

(North Korea is not alone in communist human trafficking. Cuba has long sold — or at least rented — its doctors and nurses to third world tyrants from Venezuela to Angola, as long as they could pay the Cuban regime in gold, weapons, or oil. Qatar as a petro-state, with its own record of human rights abuses, is able to finance itself with sales of natural gas.)

Qatar, desperate to complete its construction commitments for the World Cup, has turned to importing North Korean workers.

Qatar’s labor practices, in particular as they relate to the World Cup, have drawn international condemnation. Underpaid workers have to contend with day time temperatures in the summer of up to 114 degrees Fahrenheit (though under Qatari regulation employers are supposed to prevent workers from working during the middle of the day).

However, it is unclear if Qatar’s North Korean workers are being paid at all.

The State Department report builds on a 2014 report in The Guardian which reported that North Korean recruiters operating in Qatar admitted that workers themselves did not receive salaries. Instead a portion of their salaries was sent to their families with a portion going to the North Korean government.

Qatar did implement a new wage system in November 2015 under international pressure. The new system has been applied to most of the country’s 1.7 million guest workers but, it is unclear if it has been extended to North Korean workers, who are not economic immigrants making free decisions, but indentured servants supplied by a nation-state that owns them.

Last year, Qatar announced it would not give new visas to North Korean workers as Pyongyang faces increased international sanctions. However, the Qatari economy continues to send money to Dear Brother Leader Kim Jong-un.

A 2016, South Korean news article found that some 2,000 North Koreans continued to work in the country despite United Nations sanctions. They aren’t the only country. The number of North Korean workers in Kuwait is reportedly even greater than in Qatar. However, Kuwait has recently undertaken measures to reduce its economic ties with North Korea

Even without work visas North Korea is still using Qatar as a vehicle to raise money. In December UPI reported that North Korean deprived of work visas were selling bootleg alcohol to Qatar to raise money for North Korea. Around the world North Korea uses illegal alcohol sales as just another vehicle to earn hard cash for the regime.

The recent crisis and Trump’s tweets regarding Qatar suggest a new era of frank discussions with the tiny rogue emirate. As such once taboo issues are on the table North Korea labor are again on the table. Trump has even offered to mediate the Gulf dispute in the White House, an offer rejected by Qatar. With all options on the table regarding Qatar, President Trump should broach the idea of Qatar kicking out its North Korean guest workers and severing diplomatic ties with Pyongyang.