Do not use chemical weapons or else. Strong and unequivocal words from President Barack Obama to President Bashar al-Assad of Syria. For him to say these words means the threat of such seemingly disproportionate force against rebels is very real.

President says: Today I want to make it absolutely clear to Assad and those under his command: The world is watching, the use of chemical weapons is and would be totally unacceptable, and if you make the tragic mistake of using these weapons, there will be consequences and you will be held accountable."

Syrian rebels are pushing harder and advancing further, seizing military bases, blowing up tanks and cutting off army supply routes. An unverified video here from rebels claiming they'd shot down a government war plane. Fears over chemical weapons had been raised after media reports that the army were moving a stockpile of them - many concerned they were being prepared for use.

After the US President stern remarks though, Syrian TV reported words from a source at the country's foreign ministry, which spoke directly to Ban-Ki Moon, the head of the UN - he's already pulled most of his staff out of their office in the country - and Russia (with whom Syria has friendly ties) that such weapons against its people would not be used. But until a formal government statement comes to light over this, worries are sure to remain.

Written and presented by Marverine Cole