Noun
(military) An action that would justify the initiation of hostilities against the perpetrator; an action that by its nature comprises a cessation of peace.
(military) An action taken by military forces as part of a war.
Source: en.wiktionary.orgDefense is the first act of war. Byron Katie
I am an opponent of war and of war preparations and an opponent of universal military training and conscription; but entirely apart from that issue, I hold that segregation in any part of the body politic is an act of slavery and an act of war. Bayard Rustin
The essential act of war is destruction, not necessarily of human lives, but of the products of human labor. George Orwell
And each new act of war is tonight's entertainment. We're still the pawns in their game. Conor Oberst
I think the key that happened on 9/11 is we went from considering terrorist attacks as a law enforcement problem to considering terrorist attacks, especially on the scale we have on 9/11, as being an act of war. Dick Cheney
This was not an act of terrorism, but it was an act of war. George W. Bush