Michael Horton sees  the war on Yemen as a litmus test for the Trump administration:
What President-elect Trump does—or doesn’t—do about the war in Yemen will tell us a great deal about what his foreign policy in the Middle East may look like. It will also tell us which set of advisors he is most inclined to listen to: pragmatists, like incoming National Security Advisor retired Lt. General Mike Flynn, who prioritize the fight against militant Salafism, or neoconservatives who see Iranian influence as the primary threat to regional stability.
I agree that Trump’s approach to the U.S.-backed war there will tell us something important about his foreign policy, but I’m not sure how Flynn qualifies as a “pragmatist” especially when it comes to Iran. Flynn claims  to believe that the U.S. is engaged in a global war against “a working coalition that extends from North Korea and China to Russia, Iran, Syria, Cuba, Bolivia, Venezuela, and Nicaragua.” He and co-author Michael Ledeen go on to say that “Iran is the linchpin of the alliance, its centerpiece.” If we take Flynn to mean what he and Ledeen say here, how can we see him as a “pragmatist” in opposition to anti-Iranian hard-liners? For that matter, why would a “pragmatist” write a book with such a fanatical hard-liner and Iran hawk like Ledeen in the first place? For his part, Ledeen wrongly and predictably treats  the Houthis as nothing more than an extension of Iran. Why would we think that Flynn disagrees with his co-author on this? I keep coming back to Ledeen and Flynn’s book because we have the next president’s top adviser publicly giving us the outline of his worldview  at length, but it doesn’t seem to receive much attention.
If we don’t take his book as a reliable source of his views, we still have Flynn’s own testimony before Congress  in which he makes clear his hostility towards Iran and states his opinion that they are responsible for stoking the conflict in Yemen. Since Flynn exaggerates the threat from Iran and imagines a global Iran-centered “alliance” where none exists, it is unlikely that he accepts the reality that Iran’s role in Yemen has been and remains negligible. The only thing Trump has said  about the war to date confirms that he shares the erroneous view promoted by the Saudis that Iran was and is seeking to take over Yemen:
Now they’re going into Yemen, and if you look at Yemen, take a look…they’re going to get Syria, they’re going to get Yemen, unless…trust me, a lot of good things are going to happen if I get in, but let’s just sort of leave it the way it is. They get Syria, they get Yemen. Now they didn’t want Yemen, but you ever see the border between Yemen and Saudi Arabia? They want Saudi Arabia. So what are they going to have? They’re gonna have Iraq, they’re gonna have Iran, they’re gonna have Iraq, they’re gonna have Yemen, they’re gonna have Syria, they’re gonna have everything!
Trump probably got this idea from Flynn, or he picked it up from somewhere else and Flynn would be unlikely to correct it. I hope Trump ignores Flynn’s hard-line views on Iran and makes “calculated, pragmatic, and well-balanced” decisions on U.S. support for the war on Yemen and many other issues. Choosing Flynn for a top national security position strongly suggests that he won’t.