The United States annexing Hawaii in 1900 should be categorized as imperialism. The reason behind my choice is because they fought back against the royal family. The royal family tried to get Hawaii back for its natives.
In the mid-1800s, British and French governments began negotiations with Hawaii to gain economic privileges. Fearful that Hawaii would become a territory of one of these two nations; the United States signed a treaty with its Pacific neighbors to declare a friendly relationship. Annexing Hawaii was done because the united States were fearful of foreign influences in the Western Hemisphere. The Monroe Doctrine of 1823 states that any attempt by European powers to colonize in the Western Hemisphere would be viewed as hostile to the U.S.
The United States proposing the Open Door Policy in 1899 should be viewed as intervention. The open door policy stated that all European nations, and the United States, could trade with China.
This policy was proposed because it allowed multiple Imperial powers access to China, with none of them in control of that country. Through the acquisition of the Philippine Islands, and when the partition of China by the European powers and Japan seemed imminent, the United States felt its commercial interests in China threatened the U.S.
The United States declines to give aid to Hungarian Patriots in 1849 is isolationism. My research indicates that the U.S. had no reason to not aid the Hungarians. The simply jus did not wish