The latest round of NAFTA talks between the U.S., Canada, and Mexico has concluded without any major breakthroughs. The anti-trade positioning of President Trump still lingers ominously in the air. Trade, however, has not been his only target — he’s set his sights on many traditional American alliances in other spheres. This has already had at least one serious casualty.

When Canada’s foreign minister, Chrystia Freeland, announced earlier this summer that her nation would make a “substantial investment” in its military, she pointed to Canada’s southern neighbor’s pullback from its global security leadership position as the reason. As she put it, “The fact that our friend and ally has come to question the very worth of its mantle of global leadership puts into sharper focus the need for the rest of us to set our own clear and sovereign course.”

Her announcement should raise serious concerns among all North Atlantic Treaty Organization (NATO) nations, for Canada is not only America’s most reliable international ally and largest trading partner — she was America’s first true ally. The North American nations’ alliance set the stage for all trans-Atlantic partnerships that followed, including with Great Britain in World War Two and the creation of NATO in its aftermath. Freeland’s words show us why President Donald Trump’s isolationistforeign policy has already begun to undermine global security needs.

That policy was announced during the inauguration with a poisonous rhetorical flourish familiar to any student of history: “America First,” the slogan of an organization founded to keep the U.S. out of World War II. It enjoyed the support of right-wing elites and eventually merged with a similar group organized by the LEft, and its effort bore at least some fruit in helping shore up public opinion against U.S. entry into the war. Yet against this background, on August 17, 1940the United States established the country’s first-ever defense alliance. That year was a dark one in the timeline of the war, with Allied forces suffering severe defeats and Hitler’s military prowess waxing. President Franklin D. Roosevelt met that day with Canadian Prime Minister William Lyon Mackenzie King in Ogdensburg, New York, on the Canadian border. With the U.S. officially neutral in the Second World War but on a likely collision course with Nazi Germany, this alliance served America’s defense needs while avoiding entry into a war which the U.S. was not ready to fight. The North Americans agreed to create a cooperative defense arrangement, known as the Permanent Joint Board on Defense. Their agreement brought the two nations’ militaries together to share their North Atlantic Ocean regional defense responsibilities. Seventy-seven years later, representatives from both countries continue to meet on the Permanent Joint Board to explore ways to advance the nations’ mutual security needs and advise their governments on shared strategic concerns.

That agreement marked the first time the United States had officially linked its security affairs to another nation’s. Up to that point, the country had scrupulously observed what President George Washington termed in his Farewell Address the “great rule of conduct for us, in regard to foreign nations,” that “in extending our commercial relations, to have with them as little political connexion [sic] as possible.”

In a world embroiled in war, however, President Roosevelt recognized that meeting America’s security needs was no longer possible without cooperative defense arrangements. Nazi Germany had overrun most of Western Europe and threatened to invade Great Britain, among the last nations resisting Adolf Hitler’s forces. Canada served as a seagoing lifeline to the United Kingdom, providing ports for the North Atlantic convoys shuttling military supplies, fuel, food and troops to the war zone, as well as a refuge for repairing ships damaged in the relentless attacks by German U-boats at sea. At the time, an isolationist American nation to the south refused to offer anything more than moral support and sales of war materiel to prevent a German victory.

However, Roosevelt realized that should the British fall, Canada would also be endangered—and that would directly threaten the American homeland. The need for protecting American security necessitated overturning longstanding tradition. He hastily arranged a meeting with Prime Minister King. They met in the president’s train parlor car where he surprised the prime minister with his offer to create a standing defense initiative that would bring their nations’ military leader and strategic planners into close cooperation.

Roosevelt told reporters on hand that the Permanent Joint Board would help secure North Atlantic approaches to the Western Hemisphere. While he did not state it specifically, the arrangement was aimed directly at Germany, a signal to keep prowling German U-boats out of the waters nearest the United States.

After watching the parlor car summit, Secretary of War Henry L. Stimson recorded in his diary that King was so moved over the tremendous morale boost that the new alliance would bring to his people that he “almost [had] tears in his eyes.” Stimson wildly overestimated the impact of the establishment of his nation’s first mutual defense arrangement. That night, he recorded, “was very possibly the turning point in the tide of the war, and that from now on we could hope for better things.” Sadly, it would take the bombing of Pearl Harbor to shake the American people from their isolationist slumber.

But the creation of the Permanent Joint Board was important all the same: it effectively ended the long history of American isolationism. No longer would the country refuse what Washington had denigrated as “foreign entanglements.”

For three quarters of a century, military and diplomatic leaders serving on the Permanent Joint Board have continued to meet twice annually, acting as “a strategic-level military board charged with considering, in a broad sense, land, sea, air and space issues, including personnel and materiel dimensions involved in the defense of the northern half of the Western Hemisphere.” The board members have examined virtually every important joint defense measure undertaken since the end of the Second World War. These include construction of the Distant Early Warning Line of radars, the creation of the North American Air (later Aerospace) Defense command in 1958, and the bi-national operation of the underwater acoustic surveillance system and high-frequency direction-finding network. All of these hemispheric defense measures have worked to secure the United States and her northern ally from sea and air attack.