Intrusion or invasion: unlawfully entering someone’s space, property, or system; can refer to military incursions, trespassing, or hacking.
不審者が建物に侵入したため、警備が強化された。
Because a suspicious person intruded into the building, security was tightened.
ネットワークへの侵入を防ぐには、最新のセキュリティ対策が必要だ。
To prevent intrusions into the network, up-to-date security measures are necessary.
敵軍の侵入を食い止めるため、国境に部隊を配備した。
Troops were deployed at the border to stop the enemy's incursion.