protracted war; long-term battle; drawn-out contest
Used for literal wars, but also metaphorically for any prolonged struggle, such as negotiations, legal battles, or sports rivalries.
この紛争は長期戦になるだろう。
This conflict will likely become a protracted war.
価
The price negotiations have taken on the look of a drawn-out battle.
Antonym: a short-term battle or quick resolution.
Compound of 長期 (long-term) and 戦 (war, battle).