We've been here before: The durability of multilateralism.

• Author: Bosco, David

Several of the Trump administration's opening foreign policy salvoes have been aimed directly at the world's multilateral structures. The president and his nominees lambasted the UN Security Council for its December resolution declaring Israeli settlements illegal. A draft executive order reportedly called for funding cuts of up to 40 percent to the United Nations and an end to new multilateral treaties. The administration withdrew funding from the UN Population Fund and hinted that it might spurn its Human Rights Council as well. "A wave of populism...is challenging institutions like the United Nations and shaking them to their foundations," said UN Ambassador Nikki Haley.

The United Nations is far from the only multilateral target. The president quickly pulled the United States out of the Trans-Pacific Partnership negotiations and demanded changes to the longstanding North American Free Trade Agreement. His team floated the idea of tariffs on Mexico that could violate World Trade Organization rules. He pledged to review U.S. participation in the Paris Agreement on climate change. Just days before taking office, Trump called NATO "obsolete" and predicted that more members would abandon the European Union. In a sign of displeasure at what he perceives as freeloading NATO members, Trump reportedly presented German Chancellor Angela Merkel with a "bill" for underinvestment in her country's military.

The president's apparent aversion to key alliance structures and multilateralism has fed growing alarm that the administration plans to abandon the post-World War II international order. In this publication, scholar and former Obama administration official Anne-Marie Slaughter warned that "the next four to eight years may well see the end of the United Nations as a serious forum for global decisionmaking about peace and security." Jack Goldsmith, a Harvard Law professor who worked in the Bush Justice Department, called Trump's early moves "the beginnings of the greatest presidential onslaught on international law and international institutions in American history." Others have argued that China may now be more committed to key global institutions than Washington.

Major multilateral organizations like the UN, WTO, and EU and multilateral treaties are not, of course, the whole of the international order. Informal norms, habits of cooperation, and embedded power realities arguably play an even greater role in maintaining a modicum of order in the international system. But formal organizations and treaty regimes undoubtedly play an important role, which has become more prominent since the end of the Cold War. The prospect of an American administration actively undermining these instruments is unnerving.

As with much else in the administration's troubled first months, however, there's confusion about what exactly lies beneath the smoke and steam. The draft order on UN funding has been delayed for further review. Senior U.S. officials have repeatedly toned down (or openly contradicted) several of the president's most outlandish comments. Both Secretary of Defense James Mattis and Vice President Mike Pence sought to reassure European allies that Washington does...