US will put only if we sell or buy crucial nuclear technologies to non-nuclear or 'hostile' nations. CORRECTION:u mentioned US forces to deal nuclear energy with itself only which is false. Other reason would be if India conduct a "nuclear bomb" test. If India ever felt that it should test nuclear bomb as an ultimate test to its sovereignty, it can. US will put out and stop all nuclear supplies.According to 123 agreement, only nuclear supplies will be hit and not an overall economic sanction.
US cannot detect India for the following reasons: 1)US cannot lose a strategic partner. 2)India has a respectable command in developing nations. Any resolution against India will not gain acceptance in UN. Moreover, it will be vetoed by Russia if India goes against the wishes of US. 3) India is a big economy for US companies.
US has an utopian philosophy of Reagan which India should adopt which makes US the currency of the world.