It’s a trade-off. One would be a complete idiot to concentrate all resources on a sewer system while leaving an already-tense and contested border with countries that are rapidly upgrading their stike capabilities(lookup China and its borders), vulnerable.
Asia ain’t North America.
Not to mention that if 1 dollar is allocated for infrastructure & welfare in places like India,20 cents actually find their way to the project.Defense expenditure is far more closely monitored.