The United States has long encouraged its allies to increase their defense budgets and autonomy, a trend predating the Trump administration. While seemingly beneficial for burden-sharing, this push could lead to unintended consequences for US global influence and security arrangements. Experts suggest that a less dependent alliance structure might ultimately present new challenges for Washington's foreign policy.

The need for the United States to start offloading some of its global responsibilities did not begin with Donald Trump. More than a decade ago, when working as a journalist and graduate student, I heard from political scientists and other observers of US foreign relations that allies would, at some point, need to rely less on Washington and start boosting their own defence budgets; this was particularly true of America’s European and East Asian allies, facing US adversaries in Russia and...