Earlier quoted context omitted.
There are no international sanctions against Syria, simply EU sanctions and US sanctions. Countries that aren't the US and in the EU don't have to abide by that any more than the US or EU has to abide by dictats Iran or Russia or China dream up. The British action, made at the behest of the US, was at least as illegal as the response it provoked.
The EU and the US comprise several nations, so why does that not make sanctions "international"? Conversely, are international sanctions ever applied by literally every nation on earth?
For the same reason sanctions agreed on by Russia, China and North Korea (also a group comprising several nations) would not mean "international sanctions".
Not that anyone would refer to that as such anyway, of course, because we easily recognize misleading propaganda when its used by the bad guys.
> Conversely, are international sanctions ever applied by literally every nation on earth?
Nobody said literally every nation on Earth, but it should refer to more than just two political unions which are virtually joined at the hip economically, (geo)politically and even racially, and constitute a mere ~10% of the world.
UN sanctions, for example, could justifiably be called international sanctions, though there still seems no point when it's more accurate and simpler to just say "UN sanctions".