My instructor in one of my history courses in college always said we made a mistake throwing our lot in with Pakistan instead of India during the early Cold War. We saw India as almost certainly going Red due to the large population (kinda like we count California or New York as throwaways in elections) and threw in with Pakistan.
May also have had something to do with India choosing to side with USSR. No enemies on the Left, you know, and India was a proud socialist state.
Also, India was a recent colony, and therefore sympathized more with the “anti-colonial” USSR than the British-allied USA.
I understand the whole Cold-War calculus with Pakistan including the Soviet Union, but after 9/11, we should have just given up completely on Pakistan and told India - “Do what you want.”
Pakistan should now be viewed as an enemy. The goal should be to break it up into its ethnic and tribal pieces.
The idea in 1947 was that this poor country could not survive and would balkanize.
in contrast pakistan was seen as a sure bet since it was more or less homogenous (Moslem dominated and 45% Punjabi)
Also Pakistan marketed the idea that its people were the "martial races of india" while india had weak vegetarian hindu soldiers who would not be able to stand up to the USSR or china
in spite of this, ties with Eisenhower and Nehru were good and close.
The relationship deteriorated after Nehru (who for all his gullibility seemed to honestly want to be friends to all) and especially when his daughter, Indira Gandhi came to power.
They reached their Nadir in 1971 when Nixon sent a US nuclear fleet to intimidate India who was helping the Bangladeshi's get their independence from Pakistan
India was a socialist state, Sherman, but they didn't side with the USSR until after '68. Before that, they were wishy-washy, pontificating ('Gandhian values') and they were stomped by realpolitik (The Chinese had no such illusions of peace)
Population density has a stronger correlation to leftism than population total. One possibility for that is people living in closer quarters experience more envy and therefore are drawn into the politics of envy. India is socialist to the extent they can afford it. The Calcutta region is communist. Our growing military alliance with India is strategic vs. China rather than India being anti-communist, which they are not.