When the Trump administration debated how hard to bomb Syria, John Bolton, the president’s hawkish new national security adviser, suffered a surprising defeat.

This may seem like a strange thing to say, given that Trump did just bomb three Syrian government regime installations. But it’s not: Bolton was advocating a far more expansive intervention, one designed to do “ruinous” damage to the Assad regime’s military capabilities (per the Wall Street Journal).

That isn’t what happened; the strikes reportedly didn’t even destroy Assad’s chemical weapons stockpile, let alone do major damage to the conventional arsenal he’s been using to slowly grind down anti-government rebels.

The principal administration advocate for a more limited option was Defense Secretary James Mattis, with support from Joint Chiefs Chair Gen. Joseph Dunford. Mattis has long been seen as one of the most cautious and sober of Trump’s military advisers; experts on US foreign policy see the eventual outcome as a testament to his influence over the president.

“It’s ... a victory for Mattis,” says Paul Musgrave, a professor at the University of Massachusetts Amherst.

When Bolton’s appointment as national security adviser was announced last month, one fear was that he would swamp Mattis’s restraining influence. Many in Washington felt that Bolton — together with CIA Director Mike Pompeo, the hawk Trump has nominated to run the State Department — would push the president to adopt a far more aggressive approach to global crises ranging from North Korea to the future of the Iran nuclear deal.

Syria was the first big test of the influence of this so-called “war cabinet.” And they came up empty.

Why the “limited strikes” are such a defeat for Bolton

To understand how an airstrike could be a defeat for hawks, it’s really important to understand how John Bolton thinks about US intervention in the Syrian civil war.

Almost since the war broke out, Bolton has seen the conflict through the lens of geopolitics rather than a humanitarian crisis. His view is that Bashar al-Assad is an Iranian and Russian ally, and America’s primary interest in the conflict is limiting the influence of Washington’s geopolitical rivals.

“[Syria] is increasingly an Iranian satellite under Tehran’s growing regional influence,” Bolton wrote in a 2012 National Review article, near the beginning of the civil war. “Accordingly, regime change in Syria is prima facie in America’s interest.”

In 2013, when Assad first used chemical weapons on a large scale, the Obama administration threatened to launch a limited military strike — like the one that Trump just launched — in retaliation. Bolton vocally opposed the idea, specifically on the grounds that it wouldn’t be aggressive enough to have a strategic effect.

“If I were a member of Congress, I would vote against an authorization to use force here,” Bolton said in a 2013 Fox & Friends appearance. “I think the notion that a limited strike, which is what the president seems to be pursuing, will not create a deterrent effect with respect to either to Syria’s use of chemical weapons or, more seriously, Iran’s nuclear weapons program.”

Bolton, a longtime Republican, was far more supportive of Trump striking Syria after a chemical attack than Obama doing the same. Last April, when Trump launched his first strike on Syria to punish chemical use, Bolton praised the president even though the US only bombed a single Syrian airbase.

That being said, it’s clear that Bolton wanted more from the president. At the time, he called on Trump to “eliminate Syria’s Air Force,” as well as to “tell the Russians to clear out ... so they don’t become Assad’s Air Force.”

Now Bolton is in power and so should theoretically have the ability to turn these policy preferences into reality. Yet the outcome was the precise opposite of what Bolton has been clamoring for. The strikes hit three facilities linked to chemical weapons production, targets that were specifically chosen because of the limited risk of escalation and civilian casualties. The rationale was not rolling back Iranian or Russian influence, but rather narrowly tailored to deter chemical weapons use.

“The purpose of our actions tonight is to establish a strong deterrent against the production, spread and use of chemical weapons,” Trump said in an address to the nation on Friday explaining his decision. “We are prepared to sustain this response until the Syrian regime stops its use of prohibited chemical agents.”

The best explanation for why Bolton didn’t get his way is that Mattis beat him.

According to defense officials who spoke with the Wall Street Journal, Mattis opposed a bigger strike on Syria for the very reason that Bolton supported one: the possibility that it would spark a broader fight with Assad’s foreign patrons. Mattis, the Journal reports, favored a “show strike”: something that would demonstrate that mass chemical weapons use would draw a response without the risk of a broader escalation.

His fears were reportedly shared by the US’s top military officer, Joint Chiefs of Staff Chair Gen. Dunford. And the two of them appear to have triumphed over Bolton.

It’s difficult to say why Trump sided with the generals over Bolton, especially since some reports (and the president’s own tweets) suggest he favored a more aggressive response. The best inside reporting suggests that Bolton may have been hesitant to go to the mat against Mattis, who is well entrenched in the Trump administration, during his first week on the job. So it’s possible that this won’t last and that Bolton’s influence will grow over time.

But it’s nonetheless suggestive. Mattis is the longest-serving member of Trump’s national security Cabinet, by far. By this point, he knows how the president thinks and how to appeal to his instincts. This limited strike seems well-calibrated to doing just that, while simultaneously limiting the risk of escalation as much as possible. It’s possible that Mattis will consistently outmaneuver Bolton on issues like this, appealing to Trump’s more cautious instincts.

“I think that Trump places a high premium on appearances, so, thus, enforcing a red line. It’s mostly symbolic,” says Christopher Preble, a foreign policy expert at the libertarian Cato Institute. “There are clearly competing impulses within Trump’s foreign policy between wanting to appear tough, which he defines as the use of force, but not seeming to repeat the errors of his predecessors.”

These competing impulses of Trump are personified by two of his top foreign policy advisers, the aggressive John Bolton and the cautious Jim Mattis. And on the first big fight, Mattis won decisively — suggesting Bolton may not prove as influential as some hoped or as others feared.