No one was shocked when the US launched airstrikes in Syria against the Islamic State in Iraq and Syria (ISIS) on Monday. But there was a surprise twist: American warplanes and cruise missiles also hit al-Qaeda targets in Syria, specifically targeting the Khorasan sub-group that allegedly is planning attacks on the West.

In all likelihood, the Obama administration is worried that al-Qaeda stands to gain from American strikes against ISIS — and if they're not worried about this, they should be. If you weaken ISIS, the other powerful jihadi group in Syria could step into its place.

Regardless of how much effort Obama puts into bombing Khorasan, al-Qaeda may very well emerge the biggest winner from America's new war in Syria . Here's why.

ISIS and al-Qaeda are at war with one another

In order to understand how al-Qaeda could emerge as the winner from Obama's strikes in Syria, you need to understand the way in which al-Qaeda and ISIS are waging war against each other. For the most part, it's not a hot war, though the groups fought openly in Syria in 2013 (ISIS won pretty handily). It's principally a war for ideological and political control over the global Islamist movement, and the weapons are recruits, resources, and reputation.

And there's a decade of historical tension here. ISIS used to be al-Qaeda in Iraq, but al-Qaeda's Iraq branch (AQI) and the central al-Qaeda leadership were at odds for almost the entire war, as AQI resented al-Qaeda's attempts to control the war effort against America and its allies in Iraq. In 2006, AQI decided to declare a caliphate in Iraq — that's where the name ISIS originally comes from. Al-Qaeda leadership, correctly, thought this was destined to fail, and their relations fell to a historic low point. In early 2014, when ISIS was formally breaking off from al-Qaeda, it openly waged war on Jabhat al-Nusra, al-Qaeda's Syria branch. Thousands died in the fighting, which, by all accounts, ISIS won.

Moreover, both groups claim to be the one true leader of the global jihadi movement. There can be only one divinely sanctioned caliphate for all true Muslims. Both groups say they're its avatar and are competing for the same recruits, allegiance from other violent Islamist groups, funding, clerical supporters, and the like.

In the short term, there's no doubt ISIS has the momentum.

"They're drawing the largest number of foreign fighters; they're drawing the largest pile of resources right now," says Clint Watts, a senior fellow at the Foreign Policy Research Institute. "In my mind, they're very close to having won."

ISIS's loss in Syria is al-Qaeda's gain

American strategists quite rightly recognize that ISIS can't be pushed out of its territory by airpower alone. The US strategy rises or falls on the ability of CIA-trained, American-armed Syrian rebels fighting on the ground.

It's an open question whether this plan will successfully drive ISIS back. But let's imagine it really does. Who wins? There's a very, very strong case that it's al-Qaeda.

First, and most importantly, Jabhat al-Nusra, the al-Qaeda branch, has friends among the allegedly moderate Syrian rebels. "In general, ISIS' M.O. is 'there's someone with weapons, we're fighting them," explains Daveed Gartenstein-Ross, a senior fellow at the Foundation for the Defense of Democracies. "Nusra is a very different organization. It's much more embedded with other rebel groups. It works well with moderates, as well as extremists."

Take, for instance, Nusra's recent maneuvers in the south of Syria. According to the Washington Institute for Near East Policy's Andrew Tabler, Nusra is currently engaged in a campaign with several other rebel groups to to "relieve the rebel pocket southwest of Damascus" besieged by Bashar al-Assad. That's not typical ISIS behavior, to say the least.

US bombing "virtually guarantees that there will be defections from ISIS to Nusra"

According to Gartenstein-Ross, this difference in strategy is a direct result of both groups' experience with AQI's failed caliphate in Iraq during the US-led war there. Al-Qaeda "thought that one of the reasons the Iraq War was such a disaster for them was because of how much they alienated the population, and made a lot of enemies they shouldn't have," he explains. ISIS, by contrast, "is kind of like al-Qaeda in Iraq, but even more willing to crush others under its boot."

You can see why this might be a problem for the US strategy. If moderate rebels push back ISIS, they're not going to turn against Nusra, their partner in the fight against Assad. "When you start to game it out, the problems with that part of our strategy become really apparent," Gartenstein-Ross says.

So ISIS's losses would almost certainly give al-Qaeda more freedom to operate in Syria. Moreover, it would likely drive up al-Qaeda recruiting, as the potential recruits that would have gone to ISIS saw Nusra's successes.

American bombing "virtually guarantees that there will be defections from ISIS to Nusra, because defection is a way of avoiding targeting," Gartenstein-Ross explains. And globally, ISIS' claim to legitimacy depends on its ability to hold onto territory: its big recruiting advantage is that, unlike al-Qaeda, it has managed to actually create a caliphate. The more it gets pushed back, the more its recruiting well among foreign jihadis dries up — or goes to al-Qaeda.

"It's not completely zero-sum," Gartenstein-Ross says. "But it's somewhat close."

Al-Qaeda gains in Syria could be even worse for America than ISIS

On the first day of strikes in Syria, the US tried a different approach: bombing al-Qaeda leaders. The US says it hit al-Qaeda targets, and unconfirmed reports say that it killed key leaders of Khorasan, the al-Qaeda subgroup in Syria.

trading a much weaker ISIS for even a moderately stronger al-Qaeda might not be in America's interest.

But a study by the Georgia Institute of Technology's Jenna Jordan found that bureaucratized, compartmentalized groups like al-Qaeda are the least likely to be destroyed by decapitation campaigns — a claim she backs up with data from US strikes against al-Qaeda and its affiliates around the world.

As horrific as ISIS may be, al-Qaeda may be an enemy that, if strengthened, could pose more of a threat to the US. "ISIS has a lot of weaknesses," Gartenstein-Ross says. "They're too dependent on momentum, so they're not well positioned in any way to win the race for global jihadi supremacy."

Moreover, al-Qaeda is much more committed to striking the United States and its allies. As of August, a common view among experts on jihadism was that ISIS was not super-interested in or super-capable of launching terrorist attacks in the West (at least, it wasn't yet). Obama admitted as much in his September 10 address on ISIS strategy, pretty clearly saying that ISIS did not pose an immediate threat to the US. On the other hand, striking the United States is a key component of al-Qaeda strategy. It believes that "the far enemy" (the US) needs to be pushed away from the Middle East before "the near enemy" (Arab dictators) can be defeated and the caliphate can be established.

This puts another sad twist on an already-depressing policy issue: America's interests and America's humanitarian aspirations might be at odds in Syria. Al-Qaeda enjoys what advantages it has over ISIS because it's been less brutal and more strategic. Nusra positioning itself as a relatively moderate group, as absurd though that may be, has allowed the group to survive as ISIS rises. Weakening ISIS will reduce its threat to Iraqis and Syrians, but may also allow al-Qaeda to eventually become a greater danger to the American homeland.

Once again: when it comes to ISIS policy, America has no good options.