The election of Donald Trump as president of the United States has ushered in a period of unsettling uncertainty in international affairs. He has called the foundations of American foreign policy into question, but his precise intentions remain mysterious.
If Mr. Trump allows this uncertainty to continue – or worse, if he turns his back on U.S. allies and trading partners, as he has threatened to do – he risks harming America's closest friends, empowering its rivals and making the world even more dangerous.
Uncertainty during presidential transitions is nothing new. But this transition is different. During the campaign, Mr. Trump disavowed decades-old tenets of U.S. foreign policy. He cast doubt on America's commitment to its allies, describing the North Atlantic Treaty Organization as "obsolete" and suggesting that Japan and South Korea might want to acquire their own nuclear weapons.
He called for warmer relations with Russia at a moment when Moscow is working to sow discord within, and among, liberal democracies and is seeking to normalize its illegal annexation of Crimea.
He declared that he would tear up international agreements, including the North American free-trade agreement, the Paris climate accord and the Iranian nuclear deal. He articulated a mercantilist approach to trade, suggesting the imposition of mammoth new tariffs on imports. He praised waterboarding, a form of torture.
Whether Mr. Trump will pursue any of these policies is unclear. His statements have been vague, confusing and contradictory. When challenged, he has portrayed his ambiguity as a strategy to keep America's adversaries off guard and to maximize his negotiating leverage.
All the same, the danger is real. The U.S. remains the cornerstone of security and trade arrangements that have underpinned the international order since 1945. Mr. Trump is mercurial and eccentric. No one should write off his pronouncements as mere campaign rhetoric. Alliances can weather internal discord, but they cannot endure distrust among their members on the core question of whether they will come to one another's defence.
If doubts mount about America's security commitments, U.S. allies and strategic partners may have little choice but to consider alternatives. Some countries in Asia, for example, might feel compelled to bend to the nearby power they fear – China. The Baltic countries could make a similar calculation about their relations with Russia.
Others might adopt a more aggressive posture. If uncertainty persists, Japan and South Korea will face pressure to embark on major military build-ups and even to consider acquiring their own nuclear deterrents, which China would vigorously oppose. Since his election, Mr. Trump has offered reassuring messages to the Japanese and South Korean leaders, but after all the inflammatory talk in his campaign, he will need to demonstrate that his commitment is real.
Europe has been largely at peace for more than 70 years, due in part to the reassurance of the U.S. security guarantee. The last thing Europe needs, as it confronts multiple challenges, is a weaker NATO and a further-emboldened Vladimir Putin.
Trade agreements are also built on relationships of trust. Since the end of the Second World War, the global trading system has generated enormous prosperity and has lifted hundreds of millions of people out of poverty. It has also fuelled economic anxiety and has hurt people who have lost their jobs. These fears, which Mr. Trump channelled brilliantly in his campaign, are real and must be addressed by all Western countries, including by sharing the benefits of trade more broadly so that fewer people feel left behind. The solution is not, however, to threaten to rip up trade agreements and erect huge new tariff walls. We've seen this movie before – in the 1920s and 1930s – and it did not end well.
These dark scenarios illustrate the risks of Mr. Trump's ambiguity. They are all avoidable, but only if he reaffirms America's relationships clearly, consistently and publicly.
His predecessors, starting with Franklin D. Roosevelt, understood that international stability depended in part on the quality of America's partnerships and the reliability of its commitments. The U.S. is less powerful, in relative terms, than it once was, and Mr. Trump's insistence that allies contribute more to their collective defence is reasonable, including for Canada. But if his recklessness continues, it risks creating the very international instability that the U.S. has historically sought to prevent.