What was the main cause that started the opium war

The First Opium War was caused directly by China's isolationist trade policy with the West. Because China would accept only silver from the British, tension arose quickly between the two countries. Opium addiction was another main and direct cause of the opium wars. During the 1800's, opium addiction was an epidemic for the Chinese. The British quickly took advantage of the high demand of opium in China, and began widespread illegal exportation of opium to the country. This angered the Chinese to the point where it no longer would be ignored. This trade was viewed as disrespectful to the emperor and was in direct violation of Chinese law. On top of all this, the British were pushing extraterritoriality in China, basically implying that their laws and regulations were superior to China's. With tension building and neither country willing to come to a compromise, the first opium war began.

In short. The Reason the war started was because of China.

They can overthrow a presidential veto.