 Afterwards the IJA changed its strategy and deployed almost all of its existing armies in China to attack the city of Wuhan, which had become the political, economic and military center of rump China, in hopes of destroying the fighting strength of the NRA and of forcing the KMT government to negotiate for peace.On June 6, they captured Kaifeng, the capital of Henan, and threatened to take Zhengzhou, the junction of the Pinghan and Longhai railways.To prevent Japanese advances in western and southern China, Chiang Kai-shek, at the suggestion of Chen Guofu, ordered the opening of the dikes on the Yellow River near Zhengzhou.