Final answer:
The Philippines is the Southeast Asian country that gained independence from the United States in 1946 following American colonization which began in 1898.
Step-by-step explanation:
The Southeast Asian country that received its independence from the United States in 1946 is the Philippines. On July 4, 1946, the Philippines was recognized as an independent nation following a period of American colonization which began in 1898. Unlike some of its neighboring countries like Indonesia, which declared its independence in 1949 after being a Dutch colony, or Vietnam, which sought independence from French colonial rule led by figures such as Chi Minh, the Philippines' journey to independence was deeply entwined with U.S. policy after the Spanish-American War.
It is important to note the significant event prior to independence—the Japanese occupation during World War II—but following Japan's surrender and after a brief period of reoccupation by U.S. forces, the Philippines was granted its sovereignty. The establishment of the independent Republic of the Philippines marked an end to centuries of foreign rule and the beginning of a new era for the Filipino people.