Yes, that's why the UN has not been allowed to investigate...

Syria formally asks UN to probe chemical attack.  Syrian President Bashar Assad says the Syrian government has formally approached the United Nations, asking it to send in the experts to investigate the April 4 suspected chemical attack.  Assad said in an interview with the Russian state-owned RIA Novosti news agency on Thursday that the U.N. has not sent anyone yet and blamed Western nations and the United States in particular for not allowing the experts to travel to Syria.   WTOP