The Juggernaut is one of the most powerful and most feared alliances in Diplomacy: A Russo-Turkish alliance. This alliance is so called because of it's ability to just steamroller over the other countries on the board. Juggernauts are difficult to create, and they break apart easily. As Turkey and Russia are natural enemies, you are not likely to see an alliance like this very often. But if one of these does come up, you're in a heap of trouble.