Brothers to the Rescue, a Miami-based exile group, sits at the center of the latest U.S. move against former Cuban leader Raúl Castro: the Justice Department’s decision to seek an indictment over a 1996 shootdown of two civilian aircraft operated by the group. Cuban officials reacted angrily after the charges were filed, reviving a dispute that has strained relations between Washington and Havana for decades.

The case focuses on what the Justice Department alleges about Castro’s role in that shootdown, according to Associated Press reporting. Raúl Castro was Cuba’s defense minister in 1996, meaning he was the country’s highest authority after Fidel Castro at the time, AP said.

Brothers to the Rescue began operating in 1980 after a large wave of Cubans emigrated to the United States, according to AP. The group was founded by José Basulto, and its stated aim was to help Cuban refugees in the Florida straits by dropping supplies from small planes and alerting the U.S. Coast Guard. The group also became known by its Spanish name, Hermanos al Rescate.

The crisis leading up to the 1996 incident stretched across months as immigration and enforcement between the United States and Cuba became a flashpoint, AP reported. Some Cubans protested travel restrictions imposed by Fidel Castro’s communist government, and Cuba opened the port of Mariel to people who wanted to leave, filling the Florida straits with those seeking to depart. The Clinton administration then changed immigration rules to discourage Cubans from heading north on makeshift boats, while Brothers to the Rescue continued flying toward Cuban airspace in a way that AP said provoked Havana.

On Feb. 24, 1996, AP reported that three planes carrying members of Brothers to the Rescue entered a zone near the 24th parallel north of Havana, an area described by AP as close to Cuba’s highest-value targets. Cuban fighter planes shot down two unarmed civilian Cessnas, killing all four men aboard, and a third plane carrying the organization’s leader narrowly escaped, AP said.

AP also reported that two scholars this week pointed to a long-running pattern of missed warnings. William LeoGrande, a Cuba specialist at American University, and Peter Kornbluh, a senior analyst at the National Security Archive, said their 2015 book, “Back Channel to Cuba: The Hidden History of Negotiations between Washington and Havana,” shows that Clinton administration warnings about provoking Cuba did not stop Hermanos al Rescate. “Only after the shootdown did the FAA issue a concrete ‘cease and desist’ order against Basulto for what it called ‘careless or reckless’ operations that ‘endanger the lives or property of others,’” LeoGrande and Kornbluh wrote, according to AP. LeoGrande said that “there’s no good guys in this story,” arguing that Hermanos al Rescate provoking Cuba, the U.S. failing to stop the group, and the Cuban air force firing on civilian planes all contributed.

The wider legal saga connected to the 1996 shootdown also includes criminal cases in earlier years, AP reported. U.S. counterintelligence caught five Cuban intelligence agents who had infiltrated Brothers to the Rescue, and the story was later fictionalized in the movie “The Wasp Network.” AP reported that two of the agents served long sentences and three were released from custody in a prisoner exchange that came before former President Barack Obama’s detente with Raúl Castro.

In addition, AP said two Cuban fighter jet pilots and their commanding officer who were indicted in connection with the shootdown have remained outside the reach of U.S. law enforcement while living in Cuba. Lt. Col. Lorenzo Alberto Pérez-Pérez was among three people indicted in August 2003 and accused of murder, aircraft destruction and conspiracy, AP reported. At the time, the U.S. government said Cuba’s intent was “to terrorize the Cuban population” on the island and in Miami.

AP reported that Pérez-Pérez, who said he intercepted the aircraft and warned the crews based on orders from controllers, described the encounter on Cuban state television days after the shooting. “We tried to dissuade their crew members, but they continued to dangerously approach the Cuban coast and then we received the order to interrupt the flight of the first aircraft,” Pérez-Pérez said. “Afterward, we conducted the same operation with the second plane, which also refused to change its direction,” AP reported.