Now that Donald Trump has won the Republican nomination, capitalizing on his image as a nationalist tough guy, he needs to fill in some of the details on his strategic vision for a proper American role in the world. By correctly declaring the NATO alliance obsolete and urging U.S. East Asian allies, such as Japan and South Korea, to do more for their own defense, he has identified one of the most important strategic issues for a new world vision.

The post-World War II informal American Empire has been defined by U.S. protection of wealthier allied countries in Europe, East Asia, and the Middle East, many times against poorer foes; retention of hundreds of military bases overseas to do so; and profligate military and covert interventions to maintain this costly empire. In return, those allies have not even fully opened their markets to American goods and services. Trump is correct that we can no longer afford to sign up to defend countries that are now wealthy against adversaries that do not directly threaten the United States. That the United States has a $19 trillion national debt doesn’t seem to matter to the U.S. foreign policy elite, which has been reared on maintaining an inflexible strait jacket of copious foreign alliances around the world. A more independent and flexible foreign policy is needed, like that originally advocated by the nation’s founders, who counseled against “permanent” and “entangling” alliances.

So a President Trump should retract those three pillars of the U.S. Empire, so that the national debt can be reduced, thereby restoring robust American economic growth. Trump is right that we need to get our own house in order instead of trying to solve other nations’ problems. A period of economic restoration would ensure that the currently overextended America doesn’t go the way of the Soviet Union or the British and French Empires—all of which just ran out of money—into the dustbin of history. Thus, Trump’s defining America’s global interests largely in economic terms is not wrong; all other forms of national power, such as military, political, cultural, and diplomatic influence, depend on a strong economy to pay for them.

Other important security issues that a President Trump would need to address—China, Russia, Syria, and ISIS—need to be addressed within this new more restrained and restorative strategic vision. Instead of the United States automatically guaranteeing the security of European and East Asian allies vis-à-vis Russia and China, respectively, the now rich allies in each region should be the first line of defense. The United States should adopt the more independent policy of backing up those allies only if a relatively weak Russia and a rising China become hegemonic in their actions, which little evidence currently exists to assume.

As for the brutal ISIS group, the United States inadvertently created the group by invading Iraq and then converted what was a regional threat into a limited international threat by bombing the group in Syria and Iraq. U.S. intervention in the Middle East has always cost more than the oil it was allegedly protecting; now with the domestic fracking boom again making the United States the leading oil producer, the United States should care even less about local quarrels in the Middle East—in Syria, Iraq, and elsewhere. Radical Islamism has existed for centuries, and the United States should retaliate against only such groups that have a primary focus on attacking U.S. targets.

A more restrained U.S. foreign policy abroad—about which Mr. Trump has been hinting—eventually would result in less retaliatory attacks by radical Islamist and other terror groups. Most of them primarily have regional grievances and ambitions and attack the United States only because it has been a superpower meddling in the Middle East since the end of World War II.

Mr. Trump has not yet completely fleshed out a strategic vision for U.S. foreign policy, but he has made some encouraging noises. As the general election campaign proceeds, one hopes that he will fill in a more sustainable and coherent vision of America’s role in the world than the status quo represented by Hillary Clinton’s tendencies toward hawkish interventionism and military social work abroad.