American military might was crucial to the Allies\u2019 victory in World War II. But so were the military efforts of Great Britain, the Soviet Union, China, and others. America was cemented as the single \u201cindispensable nation,\u201d because America led the efforts that won the peace. America became pre-eminent by championing the Marshall Plan, the United Nations, the International Declaration of Human Rights, the North Atlantic Treaty Organization (NATO), the International Monetary Fund (IMF), the World Trade Organization (WTO), and other internationalist institutions. While not entirely benign, these efforts created a stable international system that allowed respect for human rights, self-governance, and free exchanges of ideas and goods to flourish, helping to lift billions out of misery. America remained pre-eminent because many other nations viewed America not primarily as a military victor commanding fealty and tribute, but rather as champion of a universalist vision of a better world governed by rules of fairness and decency under which America itself consented to operate. America fortified its pre-eminence by building a more just, humane world. America\u2019s behavior frequently fell short of its ideals, but it met them often enough that other nations stepped in to champion and preserve those ideals even during our lapses. Some hoped the relatively humane post-war international system America midwifed into existence had become self-sustaining and self-improving. That hope was misplaced. Right now, the system which has for over seven decades benefited so many (not least America) is being challenged by retrograde forces across the globe. All those threats combined, save one exceptional threat, are insufficient to topple that system. However, the one exceptional threat may end not only that benign system, but also America\u2019s pre-eminence. That exceptional threat is the GOP\u2019s efforts to renounce allegiance to a just international system, and to extort and bully other nations in self-defeating pursuit of hegemony. By weakening America\u2019s commitment to and global leadership of climate change mitigation, international justice, self-determination, human rights, humanitarian and developmental aid, refugee resettlement, anti-corruption, and trade liberalization, the GOP is creating massive vacuums which China and Russia are eagerly exploiting. The rest of the world recognizes the existential dangers of catastrophic climate change and will begin turning toward China for moral, institutional and technological leadership as Donald Trump squanders the global leadership role President Obama built over eight years of determined, shrewd negotiation. By breaking faith with NATO, Trump will cause Europe, less than three decades after the demise of the Iron Curtain, to fall under retrograde influences emanating from the Kremlin. In reaction to Trump\u2019s trade belligerence, the rest of the world will increasingly defer to China to lead a remade international system; that China-led system won\u2019t be as universalist or favorable to America as the current system, but to other countries will appear more attractive than Trump\u2019s self-dealing. America became great in direct proportion to its efforts to do good. By leading America to behave selfishly, the Trump GOP will sacrifice America\u2019s greatness. The Ridgefield Democratic Town Committee provides this column.