Answer:
Oceania became a supply source in 1788 for the settlement of Australia. Pigs from Tahiti were landed at Sydney in 1793, and until 1826 the trade remained important, although it was subject to price fluctuations.
To trade with island people.
There was a general fear that the European powers, especially Spain, would try and retake some of their territory in the Western hemisphere.
As a result, the Monroe Doctrine stated that the United States would not tolerate European meddling in the Western Hemisphere.