Rumors are starting to fly that James Mattis will soon be out as the US secretary of defense. Whether he resigns or is fired is an open question, but Mattis could be as gone as soon as the November midterm elections are over.

When Donald Trump became president of the United States, Mattis was one of the few people permitted a considerable degree of latitude in running his department. America’s draft-dodging president had a major man-crush on the retired four-star general, constantly referring to Mattis by his nickname, “Mad Dog” (a moniker that Mattis himself was never particularly fond of).

Trump’s awe of Mattis went hand-in-hand with his reverence for the US military. The Department of Defense (DoD) is one of the few parts of the US government where Trump wants to beef up spending. As The New York Times’ Max Fisher has put it, Trump is “fascinated with raw military might,” which he views as “synonymous with America’s standing in the world.”

Again, this may be over-compensating for his own failure to serve in the military, but in any event, Trump gave Mattis a lot more autonomy than he did any other department chief. Moreover, Trump bumped up the DoD’s budget to US$686 billion – about $80 billion more than his predecessor Barack Obama’s last defense budget – and ultimately, he wants to boost this amount to $742 billion by 2023.

Is Trump tiring of Mattis?

Trump’s love affair with Mattis may be wearing thin, however. In many cases, Mattis overplayed his hand, mistakenly believing that Trump’s hands-off attitude toward the military and the DoD would last forever. On the other hand, Trump’s natural proclivity for slavish loyalty and sycophancy on the part of his underlings gradually re-emerged when it came to Mattis, and he became increasingly unhappy with Mattis’ independence.

It didn’t help, either, that revelations in Bob Woodward’s new book, Fear, appear to show that White House aides and officials are trying to control the president and rein in his more impetuous actions. This, plus the “anonymous” op-ed in The New York Times, have only further fueled Trump’s paranoia and caused his circle of trust to grow even smaller.

In any event, Trump-Mattis clashes have increased in recent months. The defense secretary publicly declared that he had “no plans” to call off upcoming US-South Korean military exercises, even though Trump had promised North Korean dictator Kim Jong Un at their Singapore summit that he could cancel these “war games.”

In addition, Mattis has opposed Trump on a variety of issues having to deal with the US military, such a ban on transgender recruits, the creation of a Space Force, threats to reduce US commitments to the North Atlantic Treaty Organization, cutting US troop levels in Syria, Europe and Asia, and the like. He also dissented from Trump’s decision to pull out of the Iran nuclear agreement.

What next for the DoD, if Mattis leaves?

Perhaps Mattis was too naive in believing that he would have a free hand when it came to the US military. No president would give his defense secretary carte blanche over his domain, and Trump is even more adamant about demanding unquestioning, public loyalty than his forebears. And given that it is increasingly likely that Trump will clean house after the midterms, Mattis – along with Attorney General Jeff Sessions and White House Chief of Staff John Kelly – is on the outs.

In any event, it is not a good sign that Trump has begun to call Mattis “Moderate Dog” behind his back.

But how does this affect the Defense Department and the US military? In the short run, probably very little. Trump may dislike Mattis, but his love affair with the US military continues to grow (as will its budget). The New York Times’ Fisher argues that Trump sees the military as a powerful tool of coercion. Hence we might begin to see Trump using the US military more and more as an instrument for gunboat diplomacy, dispatching aircraft carriers to places like the South China Sea and marines to places like the Middle East, as a show of power.

Consequently, the status of the US military – and of whoever is appointed secretary of defense – may actually rise in the post-2018 Trump administration. But a more sycophantic defense secretary may be unable to direct Trump’s focus when it comes to the US military’s fundamental aims and objectives. Again, according to Fisher, Trump’s military thinking is almost entirely built around the concept of “winning,” but without ever defining what “winning” means.

A US military, huge and adrift?

Moreover, Trump is “little-focused” on such details as military strategy or priorities. Rather, it is the sheer size of the military – and, in addition, the size of the defense budget – that is most important to him. Military force is basically “performative” and a “symbol of strength.” As such, a large military, outfitted with the most advanced conventional and nuclear weapons, is viewed as an end in itself.

Hence if there is such a thing as a “Trump defense strategy,” it is centered almost entirely on military spending and acquisitions. Trump wants to build up the military for its own sake, in and of itself, and regardless of why or what he intends to use it for.

Without a strong hand like Mattis’ at the tiller, what the US – and, indeed, the entire world – faces is a US military that is both huge and yet also adrift. Without any clear goals as to security policy, Trump’s military buildup could be a bull in a China shop.