(CNN) -- The coalition is growing -- not just in words, but in action. Just over two weeks after U.S. President Barack Obama vowed "America will lead a broad coalition to roll back this terrorist threat" posed by ISIS, more than 50 countries have signed up, so far, to support the fight. They include new entrants Belgium, Denmark and Britain, which will all send fighter jets to Iraq to assist that nation's government and the United States in the anti-ISIS military campaign. Even the foreign minister of Russia -- which has butted heads repeatedly with Washington, including over whether the President of neighboring war-torn Syria needs to go -- signaled Friday his country is ready to back Iraq in fighting terrorists, "above all the Islamic State," which is what ISIS calls itself.
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NEW: Airstrikes happening in Syria and Iraq, U.S. defense official says
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Denmark joins anti-ISIS coalition, which now includes more than 50 countries
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The fight may last years, say British Prime Minister and U.S. officials
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Experts: Airstrikes so far have been successful, though ISIS has likely adapted
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