Trần Nhân Tông
In 1286, Kublai Khan appointed Trần Thánh Tông's younger brother, Prince Trần Ích Tắc, as the King of Đại Việt from afar with the intent of dealing with the uncooperative incumbent Trần Nhân Tông. Trần Ích Tắc, who had already surrendered to the Yuan, was willing to lead a Yuan army into Đại Việt to take the throne. Kublai Khan cancelled plans underway for a third invasion of Japan to concentrate military preparations in the south. Kublai accused the Vietnamese of raiding China, and pressed the efforts of China should be directed towards winning the war against Đại Việt.