China Burma India Theater (CBI) was the United States military designation during World War II for the China and Southeast Asian or India–Burma (IBT) theaters. Operational command of Allied forces in the CBI was officially the responsibility of the Supreme Commanders for South East Asia or China. In practice, U.S. forces were usually overseen by General Joseph Stilwell, the Deputy Allied Commander in China; the term "CBI" was significant in logistical, material and personnel matters; it was and is commonly used within the US for these theaters.

The Chinese Expeditionary Force was an expeditionary unit of China's National Revolutionary Army that was dispatched to Burma and India in support of the Allied efforts against the Imperial Japanese Army during the Japanese invasion and occupation of Burma in the South-East Asian theatre of the Second World War.