No one can honestly doubt that President-elect Donald Trump will be, by almost every measure, the least experienced person who has ever controlled the nation’s foreign policy. And as might be expected, we’re already hearing people call on national security experts to swallow their disdain for the businessman and help him out as he enters the Oval Office.

That’s not a bad idea. Trump, just like any other president, will need to rely heavily on advisers to develop policy and to get information on what’s happening throughout the world. But as history has shown, the American foreign policy machine cannot function without a head.

In Theory published a series on the importance of the presidency in developing policy back in March, specifically to see what experts and historians had to say on what form a Trump presidency might take. The consensus was that the president remains the crucial leader in developing a foreign policy agenda. In fact, thanks to an increasingly bloated foreign policy bureaucracy, the president’s understanding of the world is way more important than ever before.

Here’s an important bit from an article by Elliott Abrams, a career national security analyst who worked in the Reagan and George W. Bush administrations:

Even with clear presidential leadership, controlling the huge apparatus called the U.S. government is very difficult. The National Security Council’s size has ranged from about 50 members under George H.W. Bush to about 400 today. But it isn’t size that matters most: It’s having clear presidential guidance and knowing what the president wants, best of all by hearing it directly from him. That’s why a 400-person council may encounter diminishing returns. The most effective thing a loyalist can say in an interagency meeting is “No, the president said yesterday that he wants X and not Y. I was there, and I talked to him about it.”

In some sense, being president is like herding cats, if the cats are a bunch of ideological bureaucrats all trying to grab the ear of the nation’s leader and promote their institutional agenda. The risks of groupthink and echo chambers are high.

Historians often attribute the largest foreign policy blunders to unprepared presidents. Lyndon B. Johnson, for all his celebrated legislative instincts, had little expertise in what was going on in Southeast Asia as he managed the war in Vietnam. And although George W. Bush campaigned on a “humble” foreign policy opposed to “nation-building,” he has been criticized for relying too much on experts who influenced him to decide to invade Iraq.

We already hear concerns over the power of unelected White House advisers and “czars.” Critics often argue that these staff members subvert the Constitution and Congress and encourage presidents to expand executive powers to change policy.

The ideal president should be able to lay out and control a cohesive and well-informed foreign policy agenda with enough flexibility to allow advisers to shift priorities as needed. It’s a balance of both long-term and short-term goals, which takes much time (and the luck not to run into too many crises along to way) for presidents to develop.

It’s not too hard, then, to understand why so many foreign policy experts have opposed Trump’s candidacy over the past year, and the criticism hasn’t always been ideological (although his lean toward Russia and his disparagement of NATO will certainly be challenges for many experts). A good chunk of the opposition stems from Trump’s tendency to “[swing] from isolationism to military adventurism within the space of one sentence.”

This is not to say that Trump will inevitably fail all the foreign policy tests his administration will face. With time and expert guidance, we certainly should expect him to make the right calls as often as he trusts the people who know what they’re talking about.

The greatest liability, however, is the bigger picture — the larger global agenda. We simply can’t expect the foreign policy bureaucracy to fill in this gap.

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