What is the ruling on paying money to an armed militia to recover a seized cargo truck, knowing that the money will go into their pockets and that failure to pay will result in the loss of the vehicle?

There is no harm in paying money as a pre-emptive measure to ward off injustice or prevent the unlawful seizure of property. This is not considered prohibited bribery, for prohibited bribery is that which is given to invalidate a right or establish a falsehood. The sin in this case lies with the recipient, not the giver, as stated by Wahb ibn Munabbih and Ibn Mas'ud.