While the West happily built the liberal order over the past 70 years, with Europe at its center, the Americans had the continent’s back. In turn, as it unravels, America feels this loss of balance the hardest — it has always spent the most money and manpower to keep the system working.

The Europeans have basically been free riders on the voyage, spending almost nothing on defense, and instead building vast social welfare systems at home and robust, well-protected export industries abroad. Rather than lash back at Mr. Trump, they would do better to ask how we got to this place, and how to get out.

The European Union, as an institution, is one of the prime drivers of this inequity. At the Group of 7, for example, the constituent countries are described as all equals. But in reality, the union puts a thumb on the scales in its members’ favor: It is a highly integrated, well-protected free-trade area that gives a huge leg up to, say, German car manufacturers while essentially punishing American companies who want to trade in the region.