Ravi Ranjan asked: What is the difference between natural ally and strategic partner?

S. Kalyanaraman replies: Natural allies are normally 'birds of the same feather', while strategic partners are often ‘strange bedfellows’. Natural allies (think of America and Britain during the Second World War) share common political and cultural values—they may believe in democracy or authoritarianism; they may uphold liberal capitalism or socialism or state corporatism; they may share common historical and cultural traditions; their societal values may be more or less similar; they may practice the same religion; and so on.

Strategic partners (think of America and the Soviet Union during the Second World War) may share none of these similarities. Notwithstanding this difference, what makes two countries either natural allies or strategic partners is the common security challenge that they both face at a particular juncture in history and more importantly their decision to come together and pool their resources to deal with this challenge (think of America, Britain and the Soviet Union coming together to deal with the Fascist challenge during the Second World War).