What your saying dose not make any sence. Attacking a embasy weather or not it is under hostile control, can only be decided by those with the athorty to declare war.
Are you telling me that if chinesse terrorists attack the US embasy in china and the chinese attacked the embasey right away, there would be no war?
From the outside all you know is that your embasy has gone silent and the news out of the area is that there are forien troops in your embasy, without your permission.
That sounds like one of the first things a military would do in the event that they declared war.