The flag of Vietnamese Nationalist Party (Việt Nam Quốc dân Đảng, 越南國民黨), used since 1929 to 1945. It would be half-red/half-yellow ; red to symbolize its struggle and yellow to stand for the nation (to imply that the Vietnamese people are struggling for their independence).
Originally from vi.wikipedia; description page is/was of Vietnamese Nationalist Party (1929 - 1945).svg here.
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