Modi added one new fault-line i.e. hindu supremacy.India has many fault lines.
A lot of people think that indian invasion into east Pakistan was for BD people. It was and can be one possibility.
However it was to secure india eastern and north eastern states.
Nexal movement has not got any external support.
No country has exploited indian fault lines.
But india whenever it's get an opportunity, india never let them away. See BD issue, see Balchistan issue, see indian involvement in Sri lanka, in afghanistan etc