Thanks for all the replies and PMs, I'm digging in.

Without going too deep into anything classified, can anyone comment as to whether the amount of support and sanctuary that may have been offered materially affected the length and outcome of the insurgency?

To add clarity, I'm doing some academic research on whether our COIN best practices are based on cases where insurgents received little outside support and/or sanctuary (Kenya, Malaya, Philippines) versus insurgencies with significant outside assistance and sanctuary (Afghanistan (1), Vietnam, etc.) The next step is comparison of successful COIN examples of each type and seeing what the critical types were.

Going into it I thought El Sal was overall a non-externally supported insurgency (meaning for the terms of my paper it had some but not meaningful support), but have run across some conflicting sources, hence this question.

Niel