The Karthstan Republican Socialist League (or originally known as the Communist Party of Karthstan), or the KRSL for short, is one of the four factions in QWTF spy's JC4.
Being a faction of radical socialist ideals, and the only one of its kind in the Middle East, they use relatively outdated weapons from the Cold War such as the AK-47. They specialise in guerilla tactics, everytime Rico completes a KRSL mission, he will be awarded new silenced weapons and takedowns.
They're led by Fadel Cisto, an idealistic pissant with fascinations of the Soviet Union under Stalin, and Kim II Sung's North Korea, believing they made the countries great with communist pride and has faith that Karthstan will become the first communist nation in the Middle East. Soldiers can be seen flying North Korean flags as well as Cuban ones however, members also express different versions of communism, Fadel manages to keep them together under his wisdom to avoid fracturing the KRSL by "unifying communism" but in reality, he's a Stalinist trying to keep the KRSL together. Some members even say "for Arstotzka!". They also engage in ransom kidnappings and drug trafficking. Vehicles are sent from North Korea to Karthstan to assist the KRSL.
They also have the Reapers' symbol in the background suggesting they may have some connections to the Reapers. One member can be heard saying he has a brother in Panau who is a member of the Reapers.
It is a well-known fact that Said Farrah used to be a supporter of the KRSL until he found out the horrors of Socialism, and subsequently distanced himself from this group. The KRSL calls Said Farrah a "traitor" for betraying the communist cause.
The KRSL were not always like this back in the early days. They were originally a radical socialist/communist political party after the First Karthstani Civil War in the 1950s, they were known as the Communist Party of Karthstan or most commonly the KRSL as an alias, they were founded in 1959 as a political party, and they were quite controversial from the start due to the Cold War at the time, where Karthstan was building nuclear weapons.
During the Soviet invasion of Afghanistan in 1979, Karthstan remained neutral, but the KRSL intended to ally with the Soviets in that war. KRSL grew to become a huge party in the Karthstani Parliament in the days following the war in Afghanistan.
With time, KRSL had become the biggest party in the Parliament. After the fall of the Soviet Union, they began to decline. They continued to support North Korea's nuclear weapons program and reunification of Korea under Kim's rule.
In 2007, Said outlawed the party and executed the party's leader and General Secretary Musheer Mohammadi. Fadel will rise to power as Musheer's replacement and revived it as a militant group similar to FARC.
In 2014, a year before Just Cause 3's events, Rico arrives in Karthstan, and the player can choose the KRSL as a faction and wipe out the other factions to start a civil war and overthrow Said's regime, leading to one of the four endings.
However, if the player does not choose the KRSL, Rico will be sent to kill Fadel. He arrives at his destination and a gunfight ensues between Rico and the KRSL. Fadel is fatally wounded in the midst of the fighting. Rico walks up to him and announces his disgust for him, stating that he's no better than Said Farrah or any of the other dictators he has overthrown. Rico does, however, congratulate Fadel for taking over and transforming an outlawed political party into a paramilitary force. Rico then shoots him in the head and walks off. Then it is explained in ending 2, that the KRSL is destabilized by infighting due to members having their own versions of communism and is split into multiple factions with their own visions of Communism such as Marxism-Leninism, Stalinism, and Juche.
If Rico sided with the KRSL, then it is explained in the "Frenzy of Fraud" ending that the KRSL conquered the entire country. They then see the takeover as a revolution and then organize a Communist dictatorship by driving out the Islamists and destroying all religious and Islamic culture in Karthstan. The Secret Police has been reformed while work camps and death squads liquidating political dissents is now commonplace. Meanwhile, Fadel Cisto (now renamed as "General Secretary of the State") begins rebuilding Said's palace and renames a street to "Victory Square".