1.
charging in, rushing in, storming
To rush or charge forcefully into a place. Used for military raids, police operations, and other forceful entries.
警察が建物に突入した。
The police stormed the building.
特殊部隊が人質救出のために突入した。
The special forces stormed in to rescue the hostages.
敵陣に突入する覚悟はできている。
I am prepared to charge into enemy territory.
2.
entering a phase or period, plunging into
To enter a new phase, period, or situation, often abruptly. Used figuratively for entering recessions, overtime, final stages, and similar transitions.
試合は延長戦に突入した。
The game went into overtime.
選挙戦は最終ラウンドに突入した。
The election campaign entered its final round.
交渉は長期化し、いよいよ大詰めに突入した。
The negotiations dragged on and finally entered the crucial final stage.
USAGE:
As a する verb, 突入する takes the particle に to mark the target: ～に突入する. The figurative sense (entering a phase) is very common in news reporting.
COMMON COLLOCATIONS:
- ～に突入する: to charge/plunge into ~
- 延長戦に突入: to go into overtime
- 不況に突入: to plunge into recession
- 突入作戦: raid operation
- 大気圏突入: atmospheric reentry