The term 'Attack Without Warning' can be summarized by two crossword solutions: RAID (4 letters) and POUNCE (6 letters). RAID is a military tactic in which a large group of soldiers quickly enter an area to surprise and overwhelm the enemy. POUNCE is a verb meaning to suddenly rush or leap at someone or something, usually with the intention of attacking. Both words imply a sudden and unexpected attack, which is the essence of the phrase 'Attack Without Warning'.