During the late 1990s and early 21st century, Chinese foreign policy appeared to be focused on improving relations with Russia and Europe to counterbalance the U.S. This strategy was based on the premise that the U.S. was a hyperpower whose influence could be checked through alliances with other powers, such as Russia or the European Union. This assessment of U.S. power was reconsidered after the U.S. intervention in Kosovo, and as the 20th century drew to a close, the discussion among think tanks in China involved how to reorient Chinese foreign policy in a unipolar world. This discussion also occurred in the context of China's new security concept, which argued that the post–Cold War era required nations to move away from thinking in terms of alliances and power blocs and toward thinking in terms of economic and diplomatic cooperation.