It seems that the UN security council can hardly make an effective resolution on chemical attach in Syria because of Russia and China. Also, the US, currently, was unlikely to change its posture toward Mr. Assad “because of ‘political realities in Syria.'”
The EU is under pressure either. “Today’s chemical attack was a direct insult to the #EU.” There had already been debate about whether EU’s supplying reconstruction funds shall be conditional as “a significant political transition, or at least power sharing in Syria”.
Faced with various types of domestic issues, western countries have show no strong willingness to intervene in Syria issue and it makes all their dilemmatic condemnation looks powerless.
https://www.nytimes.com/2017/04/04/world/middleeast/syria-gas-attack.html