US and British officials say the Syrian government has allowed UN observers to begin work five days after the incident. Many specimens of the attack are to be lost in so many days. But the United Nations says there will be more samples after five days to gauge the nature of the attack. However, observers said that the samples collected would indicate the nature of the gas and the substance used in the attack , as well as the names , but could not confirm who did what. That is why the western countries do not want to be late. They say it's just a waste of time. Because they know from their own intelligence that the attack was definitely carried out by the army ; Not the rebels. However, the report that will come after the observation and examination of the United Nations , may clarify some issues. For example , what kind of substance has been used , what is the probability of it being lethal and how it has been spread, etc. This may strengthen the demands of the westerners.