ðə pɹɪsˈaɪs ɪmpˈoːɹtəns ænd ɹˈoʊl ʌv hˈaɪpoʊ ɪn pˈɛnɪtɹˌeɪɾɪŋ ðə dʒˌæpənˈiːz nˈeɪvəl kˈoʊdz hˈæzbiːn ðə sˈʌbdʒɛkt ʌv kənsˈɪdɚɹəbəl kˈɑːntɹəvˌɜːsi, ɹᵻflˈɛktɪŋ ɪntˈɜːnəl tˈɛnʃənz ɐmˌʌŋst jˌuːˈɛs nˈeɪvi kɹˌɪptəɡɹˈæfɪk stˈeɪʃənz.
The precise importance and role of HYPO in penetrating the Japanese naval codes has been the subject of considerable controversy, reflecting internal tensions amongst US Navy cryptographic stations.