The UN doesn’t have any particular claim to the word “international”, except insofar as anything they do is international because the UN itself is international.

Other organisations, or even loosely affiliated groups of nations, can do international things because the word just means something like “between nations”.

You understand that they were at war for a long time before they managed to sweep Assad and his forces away, right?

The final sudden advance may have come virtually overnight, but they’ve been fighting since the Arab spring in 2011