Pakistan and China have enjoyed strong relations, which encompass military, economic and diplomatic ties, since the 1960s. Several International Relations scholars consider the Sino-Pak entente to be a special kind of relationship in the post-war global system, since there are no natural ties or affinities of culture, religion or ideology that have existed between Islamabad and Beijing. Pakistan, the closest ally of China since the formation of the entente; rather, the close relationship appears to substantiate a fundamental premise of the Neo-Realist school of IR thought: namely, that states join in alliance with other states on the basis of power considerations, in this case a shared hostility to India.