President Trump walks from the Oval Office to board Marine One as he departs from the South Lawn of the White House on Thursday. (Jabin Botsford/The Washington Post)

Tensions between the United States and Iran escalated this week as the Defense Department disclosed plans to counter Iranian threats to U.S. personnel in the region — and as the State Department recalled non-emergency personnel from Iraq.

Like many foreign policy crises handled by the Trump administration, the latest standoff reportedly is plagued by ineffective decision-making processes between the president and his advisers. Trump weighed in on Twitter to respond to the criticisms of a process run amok.

Future historians will no doubt assess whether this particular case followed a dysfunctional process. But reports are consistent with how the White House advisory processes seem to have operated in Trump’s first two years. And there are good explanations for this pattern.

Here’s how presidents typically acquire information to make informed decisions — and why Trump breaks the mold.

Presidents typically rely on advisers to become informed

Presidents rarely have time to develop expertise on all national security issues that come across their desk. As one canonical study argues, a “president’s first essential need is information.”

Typically, presidents look to senior advisers in the defense, diplomatic and intelligence bureaucracies to fill the gap. A division of labor between the bureaucracies fosters different pockets of information and expertise. Pentagon voices provide critical military information. State Department officials proffer equally important diplomatic and political information — for instance, whether escalating tensions empower Iranian hard-liners.

What divides U.S. foreign policymakers?

Past research emphasizes that advisers’ roles can degrade decision-making because they promote policies favoring their own bureaucracies. Despite its conceptual appeal, one of us has found little evidence that where an adviser “stands” depends on where she “sits.”

While there are important nuances, other research finds that defense officials often provide recommendations no more hawkish than diplomatic officials. Alleged differences within the Trump administration on Iran exhibit similar patterns. Secretary of State Mike Pompeo and national security adviser John Bolton reportedly support more confrontational approaches compared to Chairman of the Joint Chiefs of Staff Joseph F. Dunford Jr.

Our research instead suggests that information, not policy recommendations, is the more consistent divide between bureaucracies on matters of military force. Presidents — and even dictators — tend to make better decisions when advisory processes satisfy two conditions. First, because advisers have differentiated specializations and expertise, it’s important that presidents receive information from all bureaucratic constituencies. Second, presidents benefit from institutional practices that foster deliberation across bureaucracies.

Trump, like every president, can benefit from this full range of information. But there’s no guarantee that he’ll get it — and past research suggests four reasons:

1. Trump is resistant to advice

Several traits of the president undermine information acquisition. First, the president has indicated that he’s already an expert on complex topics, despite having little experience, and thus requires no new advice. Second, it’s unclear whether the president is sufficiently inquisitive and willing to dedicate time to internalize new information. Third, research suggests that Trump’s dearth of prior foreign policy experience limits his ability to monitor his advisers and vet their ideas.

Such problems plagued George W. Bush’s planning for post-Saddam Iraq. The inexperienced 43rd president was satisfied that “lord mayors” would govern Iraqi cities. Bush remained disengaged during presentations on post-combat operations.

Trump is also prone to making sudden policy changes that unexpectedly override his advisers. He may feel emboldened as some of these decisions, while costly and strategically questionable, have arguably not yet proved catastrophic for the United States.

2. The Pentagon’s leader lacks experience

Trump has nominated a defense secretary with no prior experience formulating national security strategy. Patrick Shanahan’s professional qualifications as a corporate executive may help him coordinate the Pentagon’s sprawling bureaucracy. But many analysts say he is likely less suited for his role as the president’s adviser for defense and national security.

Specifically, Shanahan lacks his predecessors’ experience. Jim Mattis’s background was an asset in providing candid assessments that disagreed with other advisers — and sometimes Trump. Reports suggest Shanahan’s lack of experience may have affected the quality of deliberation regarding the designation of the Islamic Revolutionary Guard Corps as a terrorist organization and the recent war plan release.

Some past presidents have looked to their own military knowledge. President Dwight Eisenhower chose General Motors executive Charles Wilson to be defense secretary — but Eisenhower could rely on his own experience on strategic questions. Trump lacks Eisenhower’s military background.

3. Does the State Department have its ‘swagger’?

There are similar concerns that information will flow effectively from veteran State Department diplomats. While their perspectives would help assess how regional powers and U.S. allies might respond to a U.S.-Iranian conflict, several points suggest Trump entered office with a distrust of the State Department. Under Secretary of State Rex Tillerson, insiders described a “parallel department” that effectively segregated Trump’s senior diplomatic adviser from the experienced strategists in the State Department.

While the state of State seems to have improved since Tillerson’s departure, diplomatic posts remain vacant and officials still describe “chaotic decision-making” processes. This spring, the administration proposed cuts to the department’s budget. Given these problems, it’s unclear whether Pompeo can offer the president the full benefit of his department’s expertise.

4. Bolton is unlikely to push collaboration

Some national security advisers could mitigate the problems we’ve outlined by facilitating interagency deliberations. As adviser to President George H.W. Bush, Brent Scowcroft played the role of an “honest broker,” providing airtime to leaders from each bureaucracy to help the president make informed decisions.

John Bolton is an unlikely candidate to adopt Scowcroft’s model. Formal meetings of senior officials reportedly dwindled after the transition from H.R. McMaster to Bolton. Bolton didn’t convene a single “principals committee” meeting on exiting the Intermediate-Range Nuclear Forces Treaty. Instead, Bolton’s deeply hawkish beliefs likely incline him toward advocating specific policies — much as Henry Kissinger did — rather than ensuring the president hears all U.S. government views.

Trump will ultimately decide the next moves. Given the obstacles undermining the administration’s advisory process, he’ll likely make those decisions despite being relatively uninformed. Instincts, potentially noninterventionist ones, rather than information, could determine the trajectory of U.S.-Iranian relations.

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Tyler Jost is a postdoctoral research fellow in the International Security Program at the Harvard Kennedy School’s Belfer Center and will be a political science assistant professor at Brown University (starting in July 2019). Follow him on Twitter: @tcjost.

Robert Schub is an assistant professor in the Department of Political Science at the University of Nebraska at Lincoln.