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.
They were phased out after being replaced by wire guided missiles, which were introduced during the Vietnam War in the 1960s and 1970s.