Our leaders do not seem to understand insurgencies. Most of our approaches are ineffective, if not counterproductive. Too many lives have been lost due to ignorance and carelessness.
The Casemate Short History series. "Guerrilla Warfare: Kings of Revolution" is a compendium of prominent guerilla leaders including George Washington, Simon Bolivar, Mao Zedong and King Ibn Saud.
Given a Russian invasion scenario, the Baltic States would have no choice to preserve their independence but to fight a guerrilla war against occupying forces.