First, the weapons should be intended for use only in retaliation after a nuclear attack. Second, the possession of the weapons must be a temporaryexpedient.
首先,这些武器应当只在遭受核袭击后反击时才使用。其次,这些武器的拥有必须是一种临时的应急手段。
《柯林斯英汉双解大词典》
2
The curfew regulation is a temporaryexpedient made necessary by a sudden emergency.