US President Barack Obama has laid out a detailed strategy for how his administration plans to combat Daesh (Islamic State of Iraq and the Levant), which controls a substantial portion of Syria and Iraq. Though I have been harshly critical of Obama’s policy towards Syria for two-and-a-half-years, his new strategy reflects a mature and coherent foreign policy — albeit one that does not fully live up to his proclaimed values. That omission may yet defeat his plan.

Obama’s approach is praiseworthy for three reasons. First, it combines force and diplomacy. Second, it attaches careful conditions to the type and scope of American military action. Third, it ties the fate of these efforts to the existence and effectiveness of a broad Middle East coalition, making clear that though the US is prepared to lead, it cannot and will not assume the role of global policeman.

In the Middle East game of thrones, Obama is playing his hand as well as he can. He knows that a US-led military effort can significantly weaken Daesh, but that only a combined military-political effort can defeat it. He created political leverage for himself by drawing a clear line, announcing that the US would “expand our efforts beyond protecting our own people and humanitarian missions” only together with the newly-formed Iraqi government. If that government makes good on its promises of political inclusion, the US will help it get its country back; if not, not.

Equally important, but less evident, is the leverage that this position provides with respect to Iran. Obama never mentioned Iran during his speech; but commentators have speculated about whether his strategy gives Iran greater leverage over the US, on the theory that Iranian-backed fighters are critical to the success on the ground in the fight against Daesh. However, Iraq’s Shiite government is one of Iran’s major strategic anchors in the region; before the US began airstrikes against Daesh, it was far from certain that the Iraqi government would survive. Iran needs US airpower at least as much as the US needs Iranian-backed ground troops.

The US emphasis on a regional coalition to fight Daesh is also deft diplomacy. US Secretary of State John Kerry has made it clear that for now, Iran is not a welcome member. Iran, without which the coalition essentially becomes a Sunni front, can have a place at the table — and play a large and overt role in resolving the Syrian civil war — but only if it is willing to reach a deal to rein in its nuclear programme. There has never been a better time to do so.

Where Obama’s strategy is weakest is in reaching out to ordinary people: The networked web of human relationships that transmits rage, hatred, despair or hope, trust and loyalty. His doctrine that the US will use force to defend its “core interests”, but will mobilise others “to address broader challenges to international order”, is sound logic and good politics in a war-weary US. But, as a Syrian tweeted to me, what the world hears Obama saying is that the US will use force to avenge the deaths of two American journalists, but will stand by while 200,000 Syrians are slaughtered.

Unless US military action is seen as actually protecting the lives and property of the Iraqi and Syrian people, the US will quickly lose the propaganda war to Daesh. As many experts warn, the first time a drone strike kills a woman or child, a video of the scene and the funeral will be posted for the Muslim world to see. Even if that video does not actually increase support for Daesh, it will convince millions of Muslims that the US is up to its old military tricks: Bombing for oil, or for Israel, or simply to crush all Muslims. Those anti-American attitudes, newly hardened once again, will make it much more difficult to get the necessary intelligence against Daesh on the ground and to deprive them of the support of other Sunni militias.

That will not just hurt the US in Syria and Iraq. It will shape popular views in other Arab states, limiting their governments’ ability to work with the US. Most damaging of all, a purely strategic justification for military action — in defence of core US interests — leaves no room to do what actually needs to be done in Syria. The only way to bring Syrian President Bashar Al Assad to the negotiating table is to weaken him and Daesh. And the only legal or moral justification for striking his air force, ammunition dumps, or heavy weaponry is the international responsibility to protect his people from him — just as the US helped protect the Yezidis from Daesh. For, contrary to Obama’s claim, the brutality of Daesh is not “unique”. Al Assad has killed more than 200,000 people, mostly civilians, in a conflict that started with his government’s torture of children.

Simply talking about the responsibility to protect, as Obama once did, accompanied by even limited strikes — perhaps as punishment for Al Assad’s reported recent use of chlorine gas against civilians — will change the game quickly. Iran will understand that America’s restraint in Syria is not indefinite; Sunni governments could be shamed in the eyes of their own people for not doing more; and Daesh’s narrative of brutality will collide with a narrative of humanity. The fate of peasants has a direct and important impact on that of kings. Obama’s policy wavers between geopolitical calculations based on national interest and the rhetoric of universal values, of standing for “our common security and common humanity”. Making that rhetoric real will buy him the room for manoeuvre that is needed to pursue his policy’s geopolitical goals.

— Project Syndicate, 2014

Anne-Marie Slaughter, President and CEO of the New America Foundation, is the author of The Idea That Is America: Keeping Faith with Our Values in a Dangerous World.