In a polarized region and a complicated world, the Islamic State in Iraq and Syria (ISIS) presents a unifying threat to a broad array of countries, including the United States. What’s needed to confront its nihilistic vision and genocidal agenda is a global coalition using political, humanitarian, economic, law enforcement and intelligence tools to support military force.

In addition to its beheadings, crucifixions and other acts of sheer evil, which have killed thousands of innocents in Syria, Iraq and Lebanon, including Sunni Muslims whose faith it purports to represent, ISIS (which the United States government calls ISIL, or the Islamic State of Iraq and the Levant) poses a threat well beyond the region.

ISIS has its origins in what was once known as al-Qaeda in Iraq, which has over a decade of experience in extremist violence. The group has amassed a hardened fighting force of committed jihadists with global ambitions, exploiting the conflict in Syria and sectarian tensions in Iraq. Its leaders have repeatedly threatened the United States, and in May an ISIS-associated terrorist shot and killed three people at the Jewish Museum in Brussels. (A fourth victim died 13 days later.) ISIS’ cadre of foreign fighters are a rising threat not just in the region, but anywhere they could manage to travel undetected — including to America.

There is evidence that these extremists, if left unchecked, will not be satisfied at stopping with Syria and Iraq. They are larger and better funded in this new incarnation, using pirated oil, kidnapping and extortion to finance operations in Syria and Iraq. They are equipped with sophisticated heavy weapons looted from the battlefield. They have already demonstrated the ability to seize and hold more territory than any other terrorist organization, in a strategic region that borders Jordan, Lebanon and Turkey and is perilously close to Israel.

ISIS fighters have exhibited repulsive savagery and cruelty. Even as they butcher Shiite Muslims and Christians in their effort to touch off a broader ethnic and sectarian conflict, they pursue a calculated strategy of killing fellow Sunni Muslims to gain and hold territory. The beheading of an American journalist, James Foley, has shocked the conscience of the world.

With a united response led by the United States and the broadest possible coalition of nations, the cancer of ISIS will not be allowed to spread to other countries. The world can confront this scourge, and ultimately defeat it. ISIS is odious, but not omnipotent. We have proof already in northern Iraq, where United States airstrikes have shifted the momentum of the fight, providing space for Iraqi and Kurdish forces to go on the offensive. With our support, Iraq’s leaders have come together to form a new, inclusive government that is essential to isolating ISIS and securing the support of all of Iraq’s communities.

Airstrikes alone won’t defeat this enemy. A much fuller response is demanded from the world. We need to support Iraqi forces and the moderate Syrian opposition, who are facing ISIS on the front lines. We need to disrupt and degrade ISIS’ capabilities and counter its extremist message in the media. And we need to strengthen our own defenses and cooperation in protecting our people.

Next week, on the sidelines of the NATO summit meeting in Wales, Secretary of Defense Chuck Hagel and I will meet with our counterparts from our European allies. The goal is to enlist the broadest possible assistance. Following the meeting, Mr. Hagel and I plan to travel to the Middle East to develop more support for the coalition among the countries that are most directly threatened.

The United States will hold the presidency of the United Nations Security Council in September, and we will use that opportunity to continue to build a broad coalition and highlight the danger posed by foreign terrorist fighters, including those who have joined ISIS. During the General Assembly session, President Obama will lead a summit meeting of the Security Council to put forward a plan to deal with this collective threat.

In this battle, there is a role for almost every country. Some will provide military assistance, direct and indirect. Some will provide desperately needed humanitarian assistance for the millions who have been displaced and victimized across the region. Others will help restore not just shattered economies but broken trust among neighbors. This effort is underway in Iraq, where other countries have joined us in providing humanitarian aid, military assistance and support for an inclusive government.

Already our efforts have brought dozens of nations to this cause. Certainly there are different interests at play. But no decent country can support the horrors perpetrated by ISIS, and no civilized country should shirk its responsibility to help stamp out this disease.

ISIS’ abhorrent tactics are uniting and rallying neighbors with traditionally conflicting interests to support Iraq’s new government. And over time, this coalition can begin to address the underlying factors that fuel ISIS and other terrorist organizations with like-minded agendas.

Coalition building is hard work, but it is the best way to tackle a common enemy. When Saddam Hussein invaded Kuwait in 1990, the first President George Bush and Secretary of State James A. Baker III did not act alone or in haste. They methodically assembled a coalition of countries whose concerted action brought a quick victory.

Extremists are defeated only when responsible nations and their peoples unite to oppose them.

This article was first published in the New York Times on Aug. 30, 2014.

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John Kerry is the 68th and current United States Secretary of State. He has served in the United States Senate, and was chairman of the Senate Foreign Relations Committee.