Nuclear weapons as the ultimate deterrent constraint on great-power war: US and Russia hold the dominant arsenals; China’s stockpile is rising but still an order of magnitude smaller. Nuclear deterrence has prevented direct great-power military conflict since 1945 despite multiple proxy wars. The risk scenario for investors is not direct nuclear war but rather proxy conflicts, economic warfare (tariffs, sanctions, financial decoupling), and resource competition — all of which are below the nuclear threshold but above the level of normal economic competition.