According to Wikipedia's entry of Liberalism,  International liberalism is a school of  

thought in international relations  theory that is based on three ideas:

1.It calls into question realism's  security/warfare foundations by rejecting  

power politics in international relations. 2.Emphasis Mutual benefits and  

international cooperation 3.Recognize the role of international  

organizations and non-governmental actors in  shaping state preferences and policy choices

Supporters of liberalism often believe  in the spreading of democracy through  

cooperation. However, a more radical form  of liberal interventionism believes liberal  

international organizations or countries  can intervene in other states in order to  

pursue liberal objectives, sometimes  even through military intervention.