I addressed your point regarding annexing NE -it is unrealistic and unnecessary.
If Bangladesh is attacked by India, we should retaliate by maximising damage to Indian economy, rather than drain our own economy trying to annex hostile land.
He is just messing around man.
The whole point of any defence pact is deterrence.
Look at NATO - in the decades since inception - how many times have NATO went head on against the country they formed to take on i.e. Russia? Even after 4 years in Ukraine, they have only been passive with weapons, training and spec ops support. I don't count Iraq and Afghan war, because they weren't against any nuclear superpower.
The Mecca Pact will be similar. If Turkey and Israel get at it tomorrow - Turkey is capable on its own to handle Israel. Likewise Saudis will not call in Pakistan or Turkey for their war in Yemen, and Pakistan won't call on Saudis for war with India. The fact that Pakistan and Turkey is allied with Saudi, gives them deterrence against Iran - which is the real reason behind the Saudis wanting this pact.
Only under extremely rare and exceptional circumstances the treaty will likely to trigger clause for a combined operation. But it's the fact that you have allies who can passively support and potentially actively support you in case you are in a pickle, is a confidence booster and a deterrence to your enemy.
Bangladesh joining the pact benefits Bangladesh in the form of deterrence against India which should reduce their interference in our internal affairs. It improves our armed forces through improved training and much needed modernization expenditure that we will be required to make as part of the alliance. It should help us root out disloyal moles that India placed in our armed forces in the last 15 years under Hasina.
As for the benefit to existing pact - the founding members can utilize the geographical location as needed. Plus, less critical operations can be delegated to Bangladesh who are less experienced in warfare, while their own troops can be deployed for critical missions. For Pakistan specifically - just the inclusion of Bangladesh in the alliance will result in India deploying more troops in the Eastern wing. India already is armed to teeth on the Eastern wing as it is, but they will have to increase it even more. This will create an undue stress on India which is to Pakistan's advantage.
Those are the only reasons I can think of if the founders of the Mecca pact ever wants to let Bangladesh in.
