expression, godan verb (-mu)
drive a wedge into; wedge apart
Literal and figurative use: physically inserting a wedge to split something, or metaphorically creating a division or foothold within a group, defense, or relationship.
敵の戦線に楔を打ち込む作戦を立てた。
They devised a plan to drive a wedge into the enemy lines.
彼の発言が二人
His remark drove a wedge between the two friends.