Few possibilities:

1) Prelude to a war that throws them off balance (looking unlikely)

2) The vulnerability was about to be discovered so had to be used immediately

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Do you know where I can read more about this? 

Getting all kinds of conflicting information, like were the pagers designed with self destruct features and got hacked, or secretly injected with explosives before delivery?

Also was this a targeted attack or did thousands of innocent people just have their pagers explode?

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Do you have a source for this information?

Injected with explosives and the attack was about as targeted as is possible in military terms. Only Hezbollah operatives had these particular pagers. The only collateral damage was from others being near them when they exploded.

Secretly injected with explosives after being ordered from Taiwan.

Whether it was targeted it’s hard to say entirely but I think it was relatively targeted.