US-led security alliances in Asia face coherence crisis amid Eurasia focus

The security alliances that the US has built in Asia are losing their unity as the ongoing situations in Ukraine and Iran shift focus toward Eurasia, complicating efforts in the Indo-Pacific region. Geopolitics examines how geography affects power relationships, drawing on Halford Mackinder’s heartland theory from 1904, which sees Eurasia as the main arena for global competition. He argued that Europe and Asia together create a 'world island' with a vital core rich in resources and strategic importance. Mackinder famously stated, "Who rules Eastern Europe commands the Heartland; who rules the Heartland commands the World Island; who rules the World Island commands the world." However, this focus is now under pressure due to increased geopolitical tensions in Eurasia and the tariffs imposed by President Donald Trump.