From Longman Dictionary of Contemporary Englishfirst strikeˌfirst ˈstrike noun [countable] PMWARan attack made on your enemy before they attack you, especially an attack made using nuclear weapons
Examples from the Corpus
first strike• The reason he survived the first strike is the reason that you all escaped the second.• There was a caretaker here, in the basement, when the first strike occurred.• New Zealand took only four minutes before making their first strike with flanker Josh Kronfeld being awarded a try. 