Donald Trump’s return to office in 2025 has ushered in a wave of executive orders that have rippled across the globe, with particularly acute effects in the developing world. This article explores how the recalibration of U.S. foreign policy under his administration marked by funding freezes, multilateral withdrawals, and trade protectionism has disrupted healthcare, climate initiatives, foreign aid, trade relations, and migration flows in Africa, Asia, and Latin America. Through a detailed review of policy reversals and their on the-ground consequences, the authors illustrate how vulnerable populations now face heightened insecurity, from the collapse of HIV/AIDS programs to stalled climate finance and strained global health systems.