President Obama today listed a number of further lines that Syria must not cross.
Addressing the nation, he said: 'Syria was told quite categorically that they must not cross the red line. However, they have crossed it by using chemical weapons.
'So now we have introduced some more coloured lines they must not cross. There's a green one, and a pink one, and a blue one, and a yellow one, and they're all made out of ticky-tacky... Er, anyway, we have laid down these lines which must definitely not be crossed.
'So Syria should know that if they cross any of these lines, there will be serious consequences. Because there will then be a purple line, a turquoise line, an orange line...'