Defensive war

A defensive war (German: Verteidigungskrieg) is one of the causes that justify war by the criteria of the Just War tradition. It means a war where at least one nation is mainly trying to defend itself from another, as opposed to a war where both sides are trying to invade and conquer each other.

American supporters of war against the British argued that the War of 1812 was a defensive war.

Islamic scholar Sufyan al-Thawri (716–778), who Khadduri (1909–2007) called a pacifist, maintained that jihad (holy war) was only a defensive war.

...
Wikipedia