In 1926, the Kuomintang allied with the Chinese Communist Party to launch the Northern Expedition with the objective of unifying the country by suppressing local warlords and abrogating the unequal treaties imposed on China by the Western powers. Following the Nanking Incident, in which Kuomintang troops targeted foreign properties and personnel, Western and Japanese warships and marines were dispatched to protect and evacuate foreign nationals living in cities on the Yangtze River. As Kuomintang forces approached Shanghai, home to a large international settlement, the American minister to China, John Van Antwerpt MacMurray, requested military intervention to protect their lives and interests. The State Department directed Williams to protect lives by evacuating Americans from the interior but not to protect private property unless lives were endangered. American forces were authorized to cooperate with other foreign forces, but not to participate in joint military actions.