The North Atlantic Treaty Organization (NATO), established in 1949 for collective security against the Soviet Union, celebrated its 75th anniversary in April 2024. NATO has expanded post-Cold War, sparking debate over expansion and enlargement. Critics argue that NATO’s post-Cold War expansion impeded transatlantic burden-sharing and shifted Russian attitudes. This research explores the extent to which NATO’s addition of new members aligns with U.S. national interests. It argues that expanding NATO aligns with the US grand strategy by reinforcing the principle of engagement, crucial for maintaining strategic alliances with European partners and ensuring regional stability. This research contributes to the NATO expansion and enlargement debate by examining the addition of new NATO members through the lens of U.S. grand strategy and the idea of engagement, particularly focusing on the 2004 inclusion of the Baltic countries. It provides a counterfactual analysis of a world without NATO, emphasizing the strategic benefits to the U.S. from maintaining a strong NATO presence. The findings highlight how NATO’s continuity and expansion support U.S. security objectives, offering insights for future policy and strategic planning.