When President Barack Obama assumed the presidency of the United Nations Security Council on Wednesday, he summoned the full weight of U.S. power to a cause with seeming universal appeal: defeating the barbarism of Islamic State — or, as Obama calls the militant group, Islamic State in Syria and the Levant (ISIL).

Much of the world, however, will question how Washington can hope to achieve this without launching a wider political agenda for accountable government in the failing states of the Arab world.

They seek U.S. recognition of the diversity of legitimate interests represented today in the Security Council chamber — and of the wider diffusion of power and capital that defines this age. In short, they look for an American president who can see the world through a genuine pluralist prism.

What they hear, however, is talk of yet another global expeditionary mission driven largely by U.S. foreign and domestic politics. More than a failure of will, intelligence or even strategy, the Obama administration’s foreign policy seems marked by a failure of imagination. This will doom the White House’s attempts to forge a sustainable global alliance. What makes this failure so tragic is the lost opportunity to rethink the design of global partnerships in the midst of an expanding archipelago of diverging power, values and interests. Yet the interests of the key powers are actually more aligned than they appear to be on issues ranging from Syria to the wider Middle East, from Ukraine to East Asia. What’s needed in each case is a new strategy that begins — and doesn’t end — with consulting all the crucial parties that have a role to play in these conflicts. One that forges a mission in which every country has a stake, no matter how disparate their starting points may be.

Consider: In Syria, only President Bashar al-Assad and Islamic State have an interest in seeing the country destroyed. A return to the policy of creating a transition to broad-based government set out by former U.N. Secretary General Kofi Annan two years ago could still bring together the United States, Russia, Iran and Saudi Arabia.

In the battle against Islamic State, virtually every nation — even those whose financial support contributed to the extremists’ rise — now recognizes that a metastasizing militant group that is highly disciplined and well-armed is a threat to all.

In Ukraine, the polarized positions of both Moscow and the West aside, a basic compromise has always been apparent. It would recognize the reality of Ukraine’s ties to Russia, but enable Kiev to escape the trap of a failed state. And in East Asia, the rivalry between China and Japan is not one that either side wants to see escalate into war. But the solution requires Washington to act as a “pacific power” that will also recognize the interests, history and values of both China and Japan. An alliance of diverse, sometimes contrasting, value systems, agendas and national perspectives is no contradiction in terms. Indeed, it is only kind of alliance that reflects today’s fragmenting global landscape — and can summon common purpose among diverse parties. On Feb. 5, 2003, another U.S. leader, Secretary of State Colin Powell, staked his unique global standing on the claim that Iraqi leader Saddam Hussein possessed weapons of mass destruction. I was in the Security Council chamber that day and vividly recall the contrast between the power of Powell’s rhetoric and the weakness of his case — and the gnawing suspicion that he didn’t believe his own words.

What the United States lost on that fateful day — and in the calamitous war that followed — was the benefit of the doubt. Recovering that singular global asset may be possible. But turning back the clock to a world of unipolar dominance is not. Pluralism remains America’s strength at home. A new diplomacy of pluralism can be America’s strength abroad. But only if Washington has the confidence and imagination to abandon, finally, the costly illusion of unipolarity and embrace the opportunity to lead as first among equals.