(JTA) – National Security Adviser Lt. Gen. H.R. McMaster invoked the post-Holocaust phrase “Never Again” in calling for U.S. action in Syria. Speaking Thursday, March 15 at the U.S. Holocaust Memorial Museum in Washington, D.C., McMaster said the United States would not stand by during the deadly conflict in Syria. “We cannot stop at remembrance alone,” he said. “If we are to fulfill our promise [of] ‘Never Again,’ we must also act to protect all victims and hold all responsible parties accountable.” McMaster warned Russia and Iran that they should stop providing support to the Syrian government. The Syrian Observatory for Human Rights, a British-based war monitor, said last week that over half a million had been killed in the Syrian civil war, which started in 2011. Approximately 85 percent of the casualties were civilians killed by the Syrian government and its allies.