Kammala wannan jumlar: A 1977, a lokacin tsarkakewar cikin gida na mulkin Khmer Rouge, Hun Sen da ma'aikatan rundunarsa sun gudu zuwa Vietnam. A lokacin da
Cambodian  Vietnamese War kamar yadda Vietnam ta shirya don mamaye Cambodia, Hun Sen ya zama daya daga cikin shugabannin sojojin 'yan tawayen da Vietnam ke tallafawa. Bayan cin nasarar mulkin Khmer Rouge, an nada Hun Sen a matsayin Mataimakin Firayim Minista da Ministan Harkokin Waje na Vietnam da aka sanya &lt;a href="People%27s%20Republic%20of%20Kampuchea"&gt;Jamhuriyar Jama'ar Kampuchea/State of Cambodia&lt;/a&gt; (PRK/SOC) a 1979 yana da shekaru 26. Gwamnatin da Vietnam ta nada ta nada Sen wani iko a kan Shirin K5, dabarun dakile Khmer Rouge wanda ya ga yawan aikin farar hula a gina shinge da ma'adinan ƙasa, kodayake ba a san girman sa ba.