RIO DE JANEIRO — The assassination squad created by Argentina’s military dictatorship to target dissidents during the 1970s had, like other state programs, its own bureaucratic rules: Employees punched in at 9:30 a.m. and were entitled to a two-hour lunch. They received a $1,000 clothing allowance during their first overseas mission. And they were required to submit expense reports.

Representatives of the ultrasecret directorate, which included intelligence officers from Chile and Uruguay, settled on their next victim through a “majority vote.”

These details of the assassination program, which pursued enemies in the region and in Europe as part of the Cold War intelligence alliance known as Operation Condor, have been found in a 1977 Central Intelligence Agency report, part of a trove of newly declassified United States government documents that shed new light on the repressive tactics of military regimes in South America and on American awareness of their actions.

The exchange of over 7,500 records — which the United States formally delivered to the Argentine government on Friday as part of a deal struck during the final months of the Obama administration — is one of the largest transfers of declassified documents from one government to another.