Yakin cacar baki wani yanayi ne na siyasa da na soji tsakanin kasashen yamma, musamman Amurka da kawayenta na NATO, da Tarayyar Soviet da kawayenta na Warsaw Pact. Ya ci gaba da kasancewa tun daga karshen yakin duniya na biyu a shekarar 1945 har zuwa farkon shekarun 1990, kuma yana da alaka da hamayya tsakanin manyan kasashen biyu, tseren makamin nukiliya, yakin neman zabe, leken asiri, farfaganda, da rikicin akida. An yi amfani da kalmar “sanyi” wajen bayyana rashin daukar matakan soji kai tsaye tsakanin bangarorin biyu, ko da yake ana samun tashe-tashen hankula da kuma kira na kut-da-kut da ke kai wa duniya gaf da yakin nukiliya.