The US nuclear modernization program is slated to bring profound changes to all three legs of the nuclear triad. But with Donald Trump in office, modernization now operates in a different context. The Trump administration, in launching a new nuclear posture review, seems to have abruptly altered the Obama administration’s rationale for modernization. It has also pledged a large build-up in conventional military forces – a build-up that would exacerbate the cost pressures already constraining nuclear modernization. These developments will change the way nuclear modernization is financed and threaten the political coalitions that have supported modernization. Strategic stability will also face significant challenges, especially if Russia and China come to perceive modernization as a US attempt to limit damage during a nuclear exchange or to establish escalation dominance. Likewise, if US allies come to doubt the credibility of US defense commitments, the risk of nuclear proliferation would increase. These dangers can be limited in a number of ways – through declaratory policy, major investments in alliance consultations, and moderate acquisition policies. In the coming years, civil service and uniformed military personnel will play a crucial role as they engage foreign governments on strategic issues and present political appointees with fair assessments of the costs of provocative action. Read this free-access article in the May/June digital journal.