Your investment is welcome for Bangladesh, in fact just last week Japan opened a $6 billion credit line for Bangladesh. But, as far military ties go, other than India, all South Asian countries you mentioned already are at various stages of military alliance with China. Most of the military hardware in these countries are from China.
I am not disloyal to my adopted country, but I am free to voice my opinion based on my "realist" analysis as long as l do not do anything concrete to harm US interest. In fact by showing the impracticality of US imperial overstretch, it would not be too far fetched to say that I am securing US interest, which is my patriotic duty. I give my version of unvarnished truth, call it tough love, if you may.
Japan eventually will be forced to back down and come back to the Asian camp. US is far away, they will not loose their skin for you when it becomes too costly for them. Remember, they did not hesitate to drop 2 big ones on your country. Fellow Asian countries will never want to do that unless their existence is threatened. If you lived in the US long enough, you should know the reason for this. Japan is only about 133 miles from Asian mainland (Busan-Fukuoka). Japan cannot escape the destiny of Asian integration and inclusion within Asian based security structure. You guys need to visualize the future enough in the future and make your strategies based on that, it should not be knee jerk reaction, based on current events and difficulties.
Here is some words on US foreign policy from one of my favorite American hero, late George Carlin: