Victor Figueroa Clark, "The Forgotten History of the Chilean Transition: Armed Resistance Against Pinochet and US Policy toward Chile in the 1980s." Journal of Latin American Studies (June 2015): 1-30.
Abstract: The history of the transition to civilian rule in Chile largely overlooks or marginalizes the role of the armed and confrontational forms of resistance to the dictatorship. This article traces the pre and post-coup history of the Left’s engagement with armed forms of struggle and evaluates the effects their incorporation into the struggle against the dictatorship had upon the regime and the Reagan administration. It concludes that armed resistance was a major factor in determining US policy to Chile during the 1980s, and therefore played an important role in the transition as a whole.
Really interesting and provocative article, using a host of primary sources, both from Chile and the U.S. Clark makes the case that the militant left is mostly excluded from analyses of the transition. What he argues is that its activities actually made the Reagan administration more likely to favor a transition, fearing an unpredictable result.
One question is how much the militant left was the decisive factor versus others. It's not always ignored. Peter Kornbluh discusses it in The Pinochet File, and while acknowledging fear of instability makes the case for Pinochet's violence per se as causing a shift in the Reagan administration. The military government was becoming an embarrassment with its overreaction (though, to be fair, one could argue that overreaction isn't possible without something causing it). In The Pinochet Regime, Carlos Huneeus also notes the role of the militant left, but makes a more institutional argument about the internal divisions in the armed forces and the timing of the plebiscite itself.
These are, literally, academic debates. Clark's is provocative because it provides far more legitimacy to what were (and often still are) labeled as "terrorist" attacks. If we accept that they helped prompt a peaceful transition, then we must also accept that they are sometimes beneficial. That opens up an entirely new debate.