As the new U.S. administration pivots toward negotiating a ceasefire in the Ukraine war, the growing nuclear threat from Russia demands urgent attention. Drawing on Cold War history and negotiation research, this analysis highlights how arms control – formal or informal – can help curb nuclear risks even in the most volatile crises. German and transatlantic policy makers should therefore integrate practical arms control and risk reduction measures into ceasefire discussions to safeguard European security and prevent nuclear escalation.