March 31, 1987: Sergeant First Class Gregory A. Fronius, an Army “Green Beret” in El Salvador, died organizing the defense against the unprecedented guerrilla attack on the Salvadoran headquarters of the 4th Infantry Brigade at El Paraiso, Chalatenango. The pro-communist insurgents called themselves the Farabundo Marti National Liberation Front (FMLN).
The well-planned attack followed a visit to the camp by Cuban spy Ana Belen Montes weeks earlier. Sixty-four Salvadoran soldiers were killed and 79 wounded. Fronius, a member of the 3rd Battalion of the 7th Special Forces Group (Airborne), posthumously received the Silver Star for his combat service. Many in the U.S. Intelligence Community believe Montes provided intelligence critical to the attack by the Cuba trained and armed FMLN.
Cuba Confidential 
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“El 9 de mayo de 1986, el Ministro del Interior,General José Abrantes Fernández, solicitaba personalmente al General Mielke la reproducción ,”por los órganos especializados” de la STASI, del “pasaporte de El Salvador en el presente año”
Un cable enviado desde La Habana por el Tte. Coronel Kirchner, oficial del espionaje y representante de la Stasi en Cuba, al General Damm, Jefe de Relaciones Internacionales, confirmaba el recibo de un envío de “ayuda solidaria” en el barco “Fichtelberg” para el FMLN, su coordinación y aseguramiento con Tropas Especiales. Cable 56/d/89- Fecha 16.03.1989- 21.45 Hrs.
http://stasi-minint.blogspot.de/2011/01/pasaportes-falsos-de-el-salvador.html
Ana Belen Montes was freely advocating the Cuban cause openly on meetings,if at this time someone would have taken his time to Investigate deeply the reason why she was so supportive,this incident would have been prevented.The Minute Ana Montes began to show support for Cuba,her clearance should have ended.