What does the United States stand for among the nations of the world? While any honest observer of history could point out plenty of exceptions to the values the United States claims to champion, since the end of World War II it has generally stood for commitment to a “rules-based international order.”

This era hardly brought with it a guarantee of peace—wars cold and hot have been waged around the globe since the emergence of the United States as a global hegemon in 1945, more than their fair share begun by Americans themselves. But it has mitigated against another world war, particularly by constraining other potential superpowers, and often provided a stability that allowed for the emergence of enduring democratic institutions and international relationships.

But the “Pax Americana”—insofar as other nations can rely on knowing what the United States stands for—is over.

The U.S. attack on Venezuela and the capture of President Nicolás Maduro and his wife on Jan. 3 feels like the final nail in the coffin. Speculation from President Donald J. Trump in the days following that he could order similar action against Colombia, Cuba, or even Mexico or Greenland made it clear that when it comes to American foreign policy, the only guarantee left is that there are no guarantees.

Less than a month before Mr. Trump unilaterally sent special forces into a foreign capital, the White House released the National Security Strategy, a statement of purpose that made it clear that the past eight decades of partnership and mutual defense would be more honored in the breach than the observance.

The N.S.S. document critiques American foreign policy priorities since the end of the Cold War in unusually harsh terms, calling them “laundry lists of wishes or desired end states” that relied on a “permanent American domination of the entire world.” Instead, it offers an ethos of naked self-interest, aimed explicitly at ensuring the United States “remains the world’s strongest, richest, most powerful, and most successful country,” one freed from a “network of international institutions.”

To the limited degree that Mr. Trump’s foreign policy decisions proceed from a coherent larger strategy, the intervention in Venezuela and endorsement of a “Donroe Doctrine” suggest a new goal of overt domination of the Western hemisphere. But even that cannot fully be relied upon, with the president and his secretary of state unable to agree on what he means when he says the United States will be “running” Venezuela.

Unfortunately, the reality seems to be unpredictability, because the world’s largest military and economic power is now essentially a rogue actor. Mr. Trump has disdained any engagement with Congress to authorize his use of military force. And given the Republican majority’s general abdication of the legislature’s role in checking the executive, it seems unlikely that he will need to do so. In the place of even nominal reliance on rules and principles, both American allies and opponents are left trying to guess who Mr. Trump will bully and threaten next.

The new N.S.S. statement reveals that the administration understands past efforts at multilateralism as simply window dressing for the goals of a discredited elite. This critique should not be dismissed out of hand. Far too much military adventurism has been cloaked in the mantle of coalitions for freedom, and the United Nations owns a long list of sins of commission and omission in this area. Nonetheless, discarding the cloak and openly brandishing the sword is not an improvement.

What the N.S.S. statement scoffs at as “vague platitudes” were in fact the aspirational ideals that made international cooperation possible. They acknowledged a higher law by which the United States, its allies and its enemies are bound, even if the United States tended to consider itself that law’s arbiter. In their place, the administration now holds up no principle at all, other than whatever Mr. Trump asserts as fact after a military intervention has already begun.

While this state of affairs may force other countries to be more afraid of Mr. Trump, it cannot achieve security for the United States. Unprincipled and unpredictable military intervention will make regional conflicts more enduring and destructive. Nor will such disruption be contained by national borders, but will result in more widespread dislocation and migration—despite the N.S.S. document’s declaration that “the era of mass migration is over.”

On this issue, Venezuela itself is a canary in the coal mine: More than eight million of its citizens have left the country since 2014, and any political or economic instability that follows this attack could spur millions more to seek safety and security elsewhere. The world could again see a cycle that has repeated time and again in Latin America—an arrogant U.S. intervention producing political and economic chaos that triggers a mass migration. If nothing else, we can be sure that U.S. actions today will have long-term consequences unforeseen by the current administration.

Catholic teaching on international relations sets out a very different vision from maximal freedom of action for the most powerful leaders. St. John XXIII in “Pacem in Terris” explained “that nations are the subjects of reciprocal rights and duties” and envisioned a public authority “set up with the consent of all nations.” Pope Benedict XVI called in “Caritas in Veritate” for reform of the United Nations and transnational economic structures “​​so that the concept of the family of nations can acquire real teeth.”  Pope Francis in “Fratelli Tutti” said human solidarity requires “more effective world organizations, equipped with the power to provide for the global common good.”

What the popes recognize, beyond their hope for an international order built on justice and peace, is that even national self-interest is tied up in a more universal and global common good. While no one nation can presume to define that good for all others, abandoning it as a shared goal leaves both strong and weak nations less secure. 

Catholic social teaching may not always provide a sufficient answer for the challenges of cooperation between sovereign nations. But it is grounded in the truth that power must be answerable to a higher law if it is ever to achieve the true security and stability at which it aims, for us and for future generations.