Late last year, President Trump said he wasn’t especially worried about making senior appointments at the State Department. Why? “I’m the only one that matters, because when it comes to it, that’s what the policy is going to be,” he declared. “You’ve seen that, you’ve seen it strongly.”

This approach to diplomacy is the logical extension of the philosophy of government that Trump aired at the 2016 Republican National Convention: “I alone can fix it.” It’s a view that many of his supporters seem to applaud – seeing it as additional evidence of his “strength” as a leader. And it’s one that he’s almost certain to apply once again, for better or for worse, in the upcoming NATO summit – and his bilateral meeting with Russian President Vladimir Putin that is set to follow it.

Yet this sort of “strength” can actually be a weakness when it comes to foreign policy. The job of formulating and defending U.S. national interests has never been left solely to the president – nor should it be. We are not a monarchy; we are not a dictatorship. In a democracy, national security policy is shaped by a vast array of individuals, institutions, and interest groups. To ignore this process is both unwise and impractical.

Even in the Trump era, the government still shapes many foreign policy decisions – and wields even greater influence over their implementation. (And on issues about which Trump does not care or does not know, his administration hums along making policy without him.) But as Trump gains more confidence in his diplomatic skills, relies increasingly on his instincts and more frequently ignores his advisers, he is personalizing U.S. foreign policy to a far greater extent than did any previous president. His priorities are determined less by an overarching strategy in the pursuit of U.S. national interests than by his personal interests and individual impulses.

The president’s most pronounced foreign policy doctrine so far is simply to reject anything President Barack Obama did before. In deciding to pull out of the Paris climate accord, the Iran nuclear deal and the Trans-Pacific Partnership, Trump never explained why these decisions for withdrawal were in the U.S. national interest. He never discussed the details of any of these agreements.

Instead, he argued that these were bad deals because they were Obama deals. In place of these multilateral agreements, Trump has promised to get better deals because he personally is the ultimate dealmaker. So far, this personalization of multilateral diplomacy has produced no new agreements in their place – not even a process for negotiating new deals that might serve American national interests.

Trump applies the same principle to his dealings with our allies: All his actions are dictated by his personal relationships. Previous presidents had policy disagreements with allies but never personalized these clashes, at least not in public. In contrast, Trump frames every bilateral relationship between states in personal terms. Some he likes; others he dislikes. Japanese Prime Minister Abe is a “great gentleman.” Canadian Prime Minister Justin Trudeau is “dishonest” and “weak.” Trump has also made known his personal antipathy toward German Chancellor Angela Merkel. What purpose does that serve?

None of this, needless to say, has anything to do with objective interests vis-a-vis the countries in question. Nothing fundamental in the balance of power between the United States and Germany or the United States and Canada has changed in the past 18 months. Yet out of the blue – due to manufactured crises about Canadian dairy products and German car imports – the United States is now enduring one of its most serious challenges to alliance relations in decades, and maybe ever. This is what happens when a president allows his personal relationships to override national interests.

Trump’s personalization of foreign policy may be most pronounced in dealing with our adversaries. Trump’s whiplashing pivot on U.S. policy toward North Korea can be explained only by his personal “chemistry” with Kim Jong Un. At their Singapore summit, Trump heaped effusive praise on the North Korean dictator – and soon thereafter, in the president’s eyes, the North Korean nuclear threat simply disappeared. With Russia, all Trump seems to want is a good meeting with Putin when they meet next month. The substance — outcomes or agreements that might advance U.S. national interests — seems to be an afterthought.

There are undoubtedly moments when personal relationships in diplomacy can produce concrete outcomes of benefit to the American people. Rarely, however, do presidents or prime ministers do personal favors for each other in diplomacy on issues of consequence. Instead, they pursue what they define as their national interests. Trump would be well served to focus more on the concrete goals of his diplomacy — hopefully in consultations with foreign policy and national security experts in his government — and less on the atmospherics of his personal interactions with other leaders, good or bad. That reorientation would most certainly would serve the best interests of the United States.