That is the title of a NYT editorial.
Diplomacy doesn’t always prevent war, Syria being one example, but war becomes far more likely if there are not enough diplomats to work with other countries to resolve disagreements. Compelling examples of diplomacy working include the 2015 deal that is preventing Iran from developing a nuclear weapon; the 1995 Dayton Accords, which ended the Bosnia War; and the 1979 Israel-Egypt peace treaty. Other examples include several treaties that committed America and Russia to reduce their nuclear arsenals significantly. American diplomats have strengthened alliances, built new partnerships with countries like Cuba and Myanmar, promoted democracy so that countries are less likely to go to war with one another and created jobs by helping to open overseas markets to American business.