Partly convenient geopolitical ally (the borders were carved of the region not long after WW2 with the enforcement of the Allied forces) and partly Dominionism where a certain subsection of Christianity, predominantly Evangelicals who are very politically motivated, believe that when Israel controls Jerusalem, the holy land, that is one of the portents of the predictions made in the Book of Revalations, ushering in God's kingdom on earth and the end of time.