A cautious President Obama told an increasingly anxious world Monday that in the fight against the Islamic State of Iraq and the Levant, "a strategy has to be one that can be sustained."

On that point most would agree. The problem, however, is that the current U.S. strategy isn't sustainable, because it's not winning. And winning is essential against an Islamic terror organization that within days has claimed responsibility for blowing up a Russian jet over Egypt and carried out mass-casualty attacks in Beirut and Paris. Other countries, and other innocent victims, have been ISIL targets, too, and messages from the terror group promise more killings, including in the U.S.

While Obama was cautious during a news conference at the Group of 20 Summit in Turkey, French President Francois Hollande rightly described the stakes Monday when he declared, "We are in a war against jihadist terrorism, which threatens the entire world."

Because the threat is global, the response must come from a broad coalition of countries that share the same goal. To some degree, that's currently the case, with some Mideast and Western nations joining the anti-ISIL fight. Yet even after Paris, Obama clearly is reluctant to do more, in part because of recent U.S. military experience in Afghanistan and Iraq.

Perhaps a different lesson from Afghanistan should be heeded. That war was triggered, after all, by an attack on U.S. soil from a terrorist group based on foreign soil. Appropriately, Article 5 of the NATO treaty, which treats an attack on one NATO nation as an attack on all, was invoked.

The alliance should carefully consider whether ISIL's attack on Paris merits the same response. If so, a NATO-backed anti-ISIL military coalition would be formidable and durable. And such a show of resolve might focus the minds of diplomats seeking a negotiated settlement to Syria's civil war, which in part created the vacuum ISIL filled first in Syria, then in portions of Iraq, and subsequently in Libya and other countries.

There are other potential global coalitions that could advance the fight against ISIL. Mideast nations can and should do more militarily, especially considering the regional destabilization from Syria's collapse. Ideally, the United Nations Security Council would go beyond condemnation and be specifically prescriptive on a globally sanctioned response. Regardless, the U.S. must lead.

The Paris attacks, by design, were an attack on the world. And if the purpose of terrorism is to instill deep fear, they worked. But they must not be allowed to transform the world further. Already ISIL has contributed to the biggest refugee crisis since World War II and has threatened further security, political and economic chaos. Obama is right to insist on a sustainable strategy, but he must first admit that it has to be a new one.