(CNN) -- Are Syrian forces using chemical weapons in their years-long fight to hold on to power? That's what the head of the Israel Defense Forces intelligence research and analysis division said Tuesday, becoming the latest to allege that Damascus was employing weapons banned under international law against its own people. The claim further stoked the debate about the international community's role in Syria, where the United Nations estimated this month that 70,000 people have been killed since the conflict flared in March 2011. U.S. President Barack Obama, for one, has said the Syrian government's use of chemical weapons against its own people would be a "game changer" in how his and other nations address the crisis.
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NEW: Russia's foreign minister warns of claiming chemical weapon use without proof
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NEW: He accuses some nations of trying to "politicize the issue"
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"In all likelihood, they used sarin gas," an Israeli intelligence official says
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The top U.S. diplomat says he has not gotten confirmation of chemical weapon use
In a letter to the U.N. secretary-general in December, Syria said the @placeholder had falsely accused it of using chemical weapons.