CIA Director Mike Pompeo has been named secretary of state. (Jacquelyn Martin/AP)

Tuesday morning brought the surprise news that President Trump plans to replace Secretary of State Rex Tillerson with CIA Director Mike Pompeo and elevate Deputy CIA Director Gina Haspel to the director job.

Although tensions have been simmering between Tillerson and Trump almost from the beginning of the administration, the timing and form of the news still came as a bolt from the blue — and Tillerson appears to have been as surprised as the rest of us.

What will the shift from Tillerson to Pompeo bring? Here are some points to consider.

Trump is still new to foreign policy, and Pompeo is new to diplomacy

The president, even after a year in office, still lacks significant foreign policy experience and has relied less on his advisers than most presidents. Research has shown that foreign policy experience matters: It can improve strategic bargaining, among other benefits.

The tenure of Tillerson and the shift to Pompeo also reflects a dynamic I found in my own research. Inexperienced presidents are less likely to seek a diversity of viewpoints and are more likely to marginalize those who bring a different perspective. Just as Colin L. Powell reportedly was marginalized during George W. Bush’s first term, Tillerson found himself on the outside looking in for most of Trump’s first year in office. Pompeo is much closer to Trump, and he is more likely to provide Trump with the feeling of certainty that inexperienced presidents are likely to prefer.

Pompeo is likely to bring a mixed set of changes to Foggy Bottom. On the one hand, he is apparently well-liked at the CIA and seems to have drawn on his “building” in a way that Tillerson never did at State. That emphasis on professionalization, if it carries over, would probably be a welcome shift within the State Department. Pompeo’s close ties to Trump could also reduce the conflicting foreign policy signals that often resulted from the Trump-Tillerson tensions.

On the other hand, Pompeo will be new to the job of top diplomat. He will not have worked closely with many of the key players involved in the complicated North Korea situation, for example, at least not in the capacity of official diplomacy. If Pompeo is willing to draw experienced officials into the discussion, that will help, but there is little escaping the conclusion that relatively inexperienced people are at the helm of U.S. diplomacy at a crucial juncture.

Being secretary of state is a political role

The secretary of state, as the public face of U.S. foreign policy, is fundamentally a political role. The secretary of state — who gets more news coverage than any other Cabinet official — sends signals to outside audiences that affect how Congress and the public view Trump’s foreign policy, how it is implemented at the bureaucratic level, and how it is communicated to foreign officials.

Internationally, research shows that face-to-face diplomacy matters for signaling, communication and interpretation. Most presidents and secretaries of state use foreign travel to maintain the United States’ diplomatic network — meeting with allies, trading partners and other states of strategic importance.

Although Pompeo will be new to his diplomatic role, his closeness to Trump (both personally and in terms of his views) might help clarify some of the signals the Trump administration sends abroad. Allies and partners will still face Trump’s unpredictability, but the odds of a conflicting signal from the State Department will probably go down.

Advisers affect how policies are perceived and sold

High-level advisers and Cabinet officials also play an important role in signaling the wisdom of an administration’s policies to outside audiences, including members of Congress and the public.

My research shows that when presidents act against their advisers’ public positions, support for policies such as using military force declines markedly. The public views the use of force much more favorably, though, when the president acts as an adviser recommends.

Why? Just as criticism from within the president’s own party is more newsworthy than complaints by the opposition party, criticism from inside the president’s own team makes headlines. It acts as a “fire alarm,” drawing the attention of Congress, the media and the generally inattentive public to the foreign policy episode at hand.

Tillerson, new to politics and relatively unconnected to Trump, made his disagreement with Trump’s positions publicly known on several occasions. Pompeo is far less likely to do that. Pompeo’s hawkish positions may also help Trump in another way: If Trump makes a diplomatic move or chooses not to use military force and Pompeo publicly endorses the president’s decision, my research suggests that the unexpected support of a hawk will boost support for the president’s policy.

The buck still stops here

As I wrote in November 2016, any foreign policy adviser’s most important audience is the president himself. Pompeo’s ascendance may reduce public disagreements between the White House and Foggy Bottom, but the timing and manner of Tillerson’s firing only confirm that Trump still controls policy from the White House.

The disagreements with Tillerson allowed some window into Trump’s decision-making and gave the media, Congress and other important watchdogs information that may be more difficult to obtain under Pompeo. But Trump has clashed even with those purported to be close to him, so the absence of public conflict will not necessarily mean there is no conflict.

Ultimately, the best way to understand U.S. foreign policy in the Trump administration is to read Trump’s tweets. Just as Tillerson did Tuesday morning.

[Editor’s note: This piece draws on an article that Elizabeth Saunders originally published in the Monkey Cage in November 2016 and that was updated and republished on Aug. 23, 2017].

Elizabeth N. Saunders is an associate professor of political science and international affairs at George Washington University.