Americans have long struggled with the question of whether this country should be more involved in world affairs, or less. The contest of ideas between internationalists and isolationists has been particularly fierce among Republicans, going all the way back to Teddy Roosevelt and William Howard Taft and continuing on to the beginning of World War II.

But since the end of that war, whatever the differences in their priorities and points of emphasis, every president has chosen engagement rather than retreat, sometimes with surprising and positive outcomes. Richard Nixon forged relations with communist China; Ronald Reagan, having consigned the Soviet Union to “the ash heap of history,” went on to negotiate arms control treaties with Mikhail Gorbachev. Even those like Dwight Eisenhower and Barack Obama who argued in various ways for scaling back America’s commitments overseas insisted on a leadership role, if not the leadership role, in building an international system grounded in democratic and free-market principles.

There have been plenty of mistakes and unforeseen developments that have tested the United States and raised questions about the wisdom of its policies. But, on the whole, the world has benefited greatly from America’s guidance and its willingness to engage with allies at every step of the way. NATO, the United Nations, the World Bank and the International Monetary Fund are all part of the architecture of global security and development that American presidents helped create.

President Trump is now taking a sledgehammer to that system. His argument, if that term can apply to such an inchoate position, is that America for too long has been “losing,” a situation he has set out to correct with nonnegotiable demands and gratuitous confrontations. He promises both to achieve more and to retrench. He promises to put “America first” while at the same time condemning it to a secondary role in global deliberations. It is a bizarre and contradictory policy: In seeking to liberate the United States from international obligations, and in waging war on multilateral institutions, he is not only destroying America’s reputation as a trusted ally but also ceding the future to the very same aggressive powers, especially the authoritarian regimes of China and Russia, that he purports to protect Americans from. Meanwhile, his running feuds with the free press, the courts and Congress are diminishing America’s standing as a bastion of constitutional liberties.