Yes, the Iran sailors incident worked out fine. But there’s still a worrying lesson here.

In the 24 hours after Iran detained and then released the sailors on two small US Navy boats that had drifted into Iranian waters in the Persian Gulf, there was, as I and many others have written, a brief and tremendously silly freakout in the US over an incident that had been quickly and peacefully resolved.

But behind that silliness, there was indeed a legitimately serious issue here: hints of the still-deep divisions in Iran, just beneath the surface, between so-called moderate versus hard-line factions jostling to pull the country in two very different directions.

This incident clearly tilted in favor of Iran’s moderates, privileging diplomacy and deescalation. But the ease with which it might have gone the other way, with which Iran’s hard-liners could have decided to exploit the situation to ramp up tensions, undermine moderates, and foment hostilities with the US — and the reasons to believe they likely desire such an outcome — should be a sobering reminder that Iran’s still-deep internal divisions pose a real risk to the US and the nascent US-Iran cooling.

Iran analyst Afshon Ostovar, writing at War on the Rocks, points out that this incident coincides with a “recent uptick” in “provocative behavior” in Persian Gulf waters from the Iranian Revolutionary Guards Corps (IRGC), the military and security service that also wields substantial political power within Iran, and that is associated closely with the hard-liners.

It was the IRGC that detained and then released the 10 American sailors. So it would seem that everything worked out fine in the end. But there are hints that along the way, there may have been some push and pull between the IRGC and more moderate factions in the regime over how to handle this incident.

Ostovar points out that previous IRGC behavior suggests the group could well conclude it would be in its interests to have escalated here rather than deescalate. It sees the Persian Gulf “as an active conflict zone. It has never accepted the presence of U.S. forces in the region and considers the expulsion of those forces from the Gulf as one of its main goals.” And, in recent months, he says, “it appears that the IRGC is taking advantage of the decreased international pressure on Iran to reassert itself.”

The IRGC would also have domestic political incentive for provocative behavior here. Ostovar again: “With Iran’s parliamentary elections coming up, and with the soaring tensions between Tehran and its Gulf Arab neighbors as a backdrop, the IRGC likely feels that it needs remind everyone of its formidability.”

But the IRGC did not escalate and instead quickly released the sailors, and there’s at least circumstantial evidence suggesting that it may have been because Iran’s moderate faction won out. As the New York Times puts it, “The [IRGC] has been engaged in an open power struggle with [President Hassan] Rouhani’s government. It is still not clear who decided to release the sailors.”

US Secretary of State John Kerry, in negotiating for the sailors’ release, may have exploited this division. He reportedly told Iranian Foreign Minister Javad Zarif, “If we are able to do this in the right way, we can make this into what will be a good story for both of us.”

The point is not to prove that the IRGC disagreed with Iran’s foreign ministry over how to handle this incident and that the more diplomacy-minded foreign ministry won out. We just can’t know that for sure.

Rather, the point is that this broader fault line, regardless of how it played out here, undeniably exists. And this episode is an illustration, yes, of things working out in a way that was productive and healthy and good for both Iranian moderates and the US, but also a reminder that it very well could have gone the other way.

It is at least plausible that hard-liners at the IRGC and elsewhere in the Iranian government could have used this incident to ramp up tensions with the US, weaken moderates, and potentially even put us on a path toward conflict. And that is worth remembering, in this and every subsequent such incident, because it’s a serious risk that is not going away, no matter how chummy the US gets with Iran’s moderate faction.

That is a danger we thankfully avoided in this particular incident, but that nonetheless remains with us in the Persian Gulf and everywhere else that American and Iranian interests intersect, each of which is an opportunity for Iran’s hard-liners or its moderates to prevail over the other and pull Iran and its relationship with the US in their preferred direction.

The fact that American diplomacy with Iran’s moderates succeeded here, as Ostovar points out, “is a testament to the new avenues of diplomacy established between the Obama administration and the Rouhani government.” But it doesn’t make hard-liners such as the IRGC, its political power, or its opposition to easing US-Iran ties any less real.