nuclear attack; nuclear strike
Refers to an offensive military action using nuclear weapons. Often used in geopolitical, historical, or security contexts.
That country is concerned about the possibility of a nuclear attack.
The threat of nuclear attack escalated especially during the Cold War.
核戦争 is 'nuclear war', a broader conflict; 核攻撃 refers to a specific strike or attack within such a war.
Compound of 核 (kaku, 'nuclear') and 攻撃 (kōgeki, 'attack'). A straightforward Sino-Japanese word formed from kanji components.