John Kerry: US will build coalition to fight 'cancer' of Islamic State

US Secretary of State John Kerry said the United States will use a NATO summit next week to push for a coalition of countries to beat back incursions in Syria and Iraq by Islamic State militants who are destabilizing the region and beyond.

"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 in an opinion piece published in The New York Times on Saturday.

Public anger over the beheading of American journalist James Foley has led President Barack Obama to consider military strikes against Islamic State targets in Syria. So far, the United States has limited its actions to the group's forces in Iraq.

The militant group, also referred to as both ISIS and ISIL, has seized about a third of each country and declared a caliphate, a reference to an Islamic state ruled by a caliph, which indicates a successor to the Prophet Mohammad, with temporal authority over all Muslims.

Kerry said he and Defense Secretary Chuck Hagel will meet with their European counterparts to enlist support for a coalition to act against Islamic State militants. "The goal is to enlist the broadest possible assistance," he wrote.

Hagel and Kerry will then travel to the Middle East to shore up support from countries directly affected by the Islamic State threat, he said.

Islamic State fighters have exhibited "repulsive savagery and cruelty" as they try to touch off a broader sectarian conflict, Kerry wrote, and the beheading of Foley "shocked the conscience of the world."

"Already our efforts have brought dozens of nations to this cause," he said. "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."

Republicans and Democrats in Congress have called for lawmakers to vote on whether the United States should broaden its action against Islamic State.

Two prominent Republicans criticized Obama on Saturday for saying the United States has not yet developed a strategy for confronting Islamic State in Syria.

In an opinion piece also published on the op-ed page of Saturday's New York Times, Senators John McCain and Lindsey Graham called Obama's statement on Thursday "startling" and "dangerous" and said the threat from Islamic State requires "a far greater sense of urgency" than the administration is showing.

McCain and Graham, in an essay headlined "Stop Dithering, Confront ISIS," suggested revising the Authorization for Use of Military Force so it could be used for evolving terrorism threats like Islamic State.

That would negate any need for members of Congress to approve specific military action against the group, or suffer the consequences of such a decision.

(Editing by Sandra Maler and Leslie Adler)