two-front war
A military or strategic situation where a force must fight on two separate fronts simultaneously. Often used in historical or geopolitical contexts.
Germany was forced into a two-front war in World War II.
A two-front war is considered something to avoid because it disperses military strength.
Compound of 二 (two), 正面 (front), and 作戦 (operation). The term is a direct calque from the military concept of a two-front war.