They were phased out after being replaced by wire guided missiles, which were introduced during the Vietnam War in the 1960s and 1970s.
ðeɪ wɜː fˈeɪzd ˈaʊt ˈæftɚ bˌiːɪŋ ɹᵻplˈeɪst baɪ wˈaɪɚ ɡˈaɪdᵻd mˈɪsəlz, wˌɪtʃ wɜːɹ ˌɪntɹədˈuːst dˈʊɹɹɪŋ ðə vˌiːətnˈɑːm wˈɔːɹ ɪnðə nˈaɪntiːnhˈʌndɹɪd sˈɪksti z ænd nˈaɪntiːnhˈʌndɹɪd sˈɛvənti z.