The inaction on the part of the world

Not the whole world Jim.
Western countries have imposed arms and trade embargoes that would have brought Assad down had not Russia refused to co operate.

He could not have sustained his military but for Russian supplies.
The oil embargo has drained away his currency reserves and halved the value of the Syrian pound.

there have been concerted political, diplomatic, economic and financial measures taken against him, but only by Western countries.

The Western nations have also pushed hard for UN action but every attempt was thwarted by Russia and China.

So, will you recognise what the Western countries have done, and condemn Russia China and Iran for propping Assad up and keeping him in power and providing all his killing resources?