collision course --------- 不可避免的冲突（成语）

英文释义
(IDIOM) A path that will inevitably lead to conflict and disaster.

例句
Their recent border disputes have put the two great nations on a collision course, and many people believe a terrible war will start soon.
最近的边界争端让这两个大国的冲突不可避免，很多人相信可怕的战争即将降临。