A U.N. watchdog agency is blaming the Syrian government for a sarin gas attack on a rebel-held area of the country that killed more than 90 people in April.The Organization for the Prohibition of Chemical Weapons, which confirmed in June that the agent used sarin, now says it is sure that the attack in Khan Sheikhoun in the northern province of Idlib was carried out by the Syrian government of President Bashar al-Assad.Linda Fasulo, reporting for NPR from the United Nations, says the OPCW conclusion "coincides with initial findings by Washington in April, which resulted in a retaliatory U.S. missile strike against a Syrian airbase."U.S. Ambassador to the United Nations Nikki Haley said in a statement that the report "confirms what we have long known to be true. Time and again, we see independent confirmation of chemical weapons use by the Assad regime."As NPR's Merrit Kennedy wrote in June: