Dear, the main contentious issue with the Chakmas was there ever since the Pakistan-era.
During the 60s, the Pakistan government wanted to construct a hydroelectric dam, and this required the Chakma tribes to evacuate their lands. They were promised compensation. They never got it. This issue still runs to this very day.
Sorry I couldn't post any sources (not everything is on the Internet), but that's the reality since I have spoken to them and Chittagongians during my visit to Rangamati. Myself am a southerner, Chittagong.
Note, the Chakma and Hmong tribes were some of the wealthiest tribes in the region. And they have been there for eons.
Why was India interested during the Cold War? That's because someone was upset that India did not get the CHT region when the British carved up both India and Pakistan. Congress expected that the CHT region be a part of India, but instead made it to Pakistan.
Bangladesh Army fought a brutal campaign during the CHT insurgency, with international support, and did so with success. Yes, even America supported us during the campaign. So no potential for American/Israeli (lol) conspiracy there.
Now, military presence is gradually going down in the CHT region.
Jeez, really off-topic aren't we guys?