According to a report by the Wall Street Journal , Bashar Al-Assad has begun scattering his massive stockpile of chemical weapons to as many as 50 different sites across the country. The US newspaper claimed in a report Friday that a secretive military unit at the center of the Syrian chemical weapons program had been charged with moving the lethal stockpile, making it difficult for the international community to track. The newspaper cited US and Europeans intelligence agencies as saying: "Unit 450 is in charge of mixing and deploying chemical munitions, and it provides security at chemical sites." The move is in contrast to commitments made by Assad to hand over his chemical weapons in a Russian deal that would prevent a military strike on his regime. As recently as Friday morning, the UN announced that it had received a letter from the Syrian government asking to join the Chemical Weapons Convention , an international arms control agreement which outlaws the production, stockpiling, and use of chemical weapons. The US threatened an attack on Syrian military installations following its accusation that Assad was behind a sarin gas attack on the Damascus suburb of Ghouta on August 21 the US says killed more than 1400 civilians. The report in the Wall Street Journal quoted US officials as saying the recent move had led to increased doubts among intelligence agencies as to the locations of Syria's chemical weapons: "We know a lot less than we did six months ago about where the chemical weapons are," one official was quoted as saying. The report also suggested that any future US strike would need to be careful it did not destabilize unit 450 which it said had Syria's estimated 1000 tonnes of chemical weapons under tight security. "If you attack them you may reduce the security of their weapons, which is something we certainly don't want," the report quoted Jeffrey White, a veteran of the Defense Intelligence Agency and a defense fellow at The Washington Institute. The report also stated that although tracking the movement of the weapons was not always easy to do, when chemical munitions were deployed in the field, Unit 450 would need to pre-deploy heavy equipment to chemical mixing areas, which the US. and Israel were able to track. As US-Russian talks to formulate a response to the crisis continue in Geneva, US Secretary of State John Kerry issued a warning to the Syrian President that a US strike was still possible.