Kerry: 'The cancer of ISIS will not be allowed to spread'

(CNN) -- ISIS is a cancer that must be stamped out, U.S. Secretary of State John Kerry wrote Saturday in an opinion piece for The New York Times.

Kerry called the Islamist extremist group, known for beheadings, crucifixions and terror campaigns against religious and ethnic minorities, a 'unifying threat to a broad array of countries' that needs to be confronted.

His article appears in the aftermath of the political uproar that engulfed the White House this week after President Barack Obama said 'we don't have a strategy' on ISIS in Syria.

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The Islamic State in Iraq and Syria, which refers itself as the Islamic State, has grabbed headlines just as certainly as it has gobbled up territory across northern Iraq over the summer.

The next move

U.S. airstrikes against ISIS fighters have slowed their advance, and the Obama administration is weighing whether to expand the assault into Syria.

But, Kerry said, any decision will require a joint effort with international partners.

'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,' Kerry wrote. 'The world can confront this scourge, and ultimately defeat it. ISIS is odious, but not omnipotent.'

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The secretary of state's message echoes that of the White House, with both the president and his press secretary Josh Earnest calling this week for an international coalition to confront the threat.

'Airstrikes alone won't defeat this enemy. A much fuller response is demanded from the world,' Kerry wrote.

To build that coalition, Kerry, along with Defense Secretary Chuck Hagel, will meet with European allies on the sidelines of the NATO meeting in Wales next week.

Then, it's off to the Middle East to drum up support from the region.

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'Already our efforts have brought dozens of nations to this cause,' Kerry argued in the Times piece. '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.'

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