ðɪ ˌɑːpɚɹˈeɪʃən bɪɡˈæn ˌɔn fˈoːɹ ɑːktˈoʊbɚ tˈuː θˈaʊzənd wˈʌn æz wˈʌn ʌvðɪ ˈeɪt nˈeɪɾoʊ ɹᵻspˈɑːnsᵻz tə ðɪ ɪlˈɛvən sɛptˈɛmbɚɹ ɐtˈæks, ɔːlðˈoʊ ɪt dɪdnˌɑːt fˈɔːɹməli bɪɡˈɪn ʌntˈɪl sˈɪkstiːn ɑːktˈoʊbɚ.
The operation began on 4 October 2001 as one of the eight NATO responses to the 11 September attacks, although it did not formally begin until 16 October.