Define extreme circumstances
Alright I'll try to invent a scenario where I'd consider a terrorist a freedom fighter.
Country A sits on the border with Country B.
The people of Country A decide they want to carve out an empire for themselves, starting with Country B.
Country A is vastly superior to country B. Country B's military is crushed by Country A in a matter of days, and the country occupied.
Country A's soldiers behave like beasts in Country B. Killing, raping, looting, burning, doing whatever they want, whenever they want. They also start massacring entire towns, and people from Country A start coming over the border and taking possession of these massacred towns.
What's left of Country B's forces know they can't fight Country A. So they slip over the border into Country A. They announce that Country A must leave Country B, and for as long as they don't, people will die. Then they start killing people. The people that supported the invasion. They can't beat the soldiers, but if they kill enough people, they can make the people call the soldiers back.