Yeon Gaesomun's coup d'état came as the culmination of a lengthy power struggle between those in the government who favored appeasement toward Tang China and those who advocated military confrontation; Yeon Gaesomun belonged to the hard-liners. Traditional Chinese and Korean historians assumed that Yeon Gaseomun's motive was simply his thirst for power, but many modern Korean historians assert that his motive was to make Goguryeo assume a tougher stance against Tang China, as opposed to King Yeongnyu who submitted to Tang for a peaceful diplomatic relationship. Yeon Gaesomun's role in the murder of King Yeongnyu was taken as the primary pretext for the failed Tang invasion of 645.