The ERP was an extremely militant faction of the FMLN. It believed that military action more than political action would propel the guerrillas to power. The ERP had strong ties to Cuba and was inspired by other Latin American guerrilla groups such as the Montoneros, Tupamaros, the Chilean MIR, and the Colombian M-19. Its actions and organization often reflected these ties. The FPL, concerned with the idea of prolonged popular war, concentrated more on building long-lasting infrastructure. Its emphasis was more focused on creating units and structures. The ERP was concerned more with action, and its focus was more on organizing for specific operations. While the ERP had special forces cadres, it did not create an official special forces unit until 1982, while the FPL had units as early as 1980. However, the ERP did carry out special forces missions. The ERP planned a mission, and then trained individuals in special techniques to carry out those missions. Later, when the ERP did form special forces units, the specially trained individuals became the core cadres of the special forces units. One of the earlier special missions was the attack on the National Police headquarters.
Two separate factors played a part in this operation. First, the ERP had an infiltrator, subsergeant Jose Jacinto Mendoza, in the National Police. Jose's brother Mauricio had been a guerrilla. He had been killed by the security forces in 1978, and ever since then Jose had wanted to avenge his brother's death. Until now he had carried out intelligence missions among the enemy ranks, and had provided valuable information to the ERP. How-