[Zakāh Issues 1]

Answer—and Allah is the One who grants success: Averting great harm by means of lesser harm is permissible according to sound intellects, and the Prophet (May Allah bless him and his family and grant them peace) was on the verge of proposing to the polytheists during the Battle of the Trench a third of the date harvest of Madinah in return for their withdrawal from their attack.
And in the words of Imām al-Hādī—peace be upon him—to the effect that: it is permissible for the imām, when there is need, to take from the subjects what he uses to repel the enemy from the lands of the Muslims—even by coercion.
If the matter is as the questioner has described, it is permissible for him to remain; rather, that is preferable.
This may be indicated by His saying, Exalted is He: “except when taking precaution against them in prudence.” [Āl ʿImrān:28] What the questioner has mentioned is a form of prudent precaution (taqiyyah) accompanied by righteous intention.
Yes—what we have mentioned is specific, and thus it specifies the general evidences forbidding assisting the unjust and the disbelievers.
Some scholars have said that it is permissible to pay a bribe in order to extract a definitive right, even though it is impermissible for the recipient to take it; and they mentioned that it is permissible to aid the lesser wrongdoer against the greater wrongdoer.
All that we have mentioned indicates that averting great harm by means of small harm is permissible; this is imprinted in the very nature of reason, as we have said.
Among the supports for this innate principle is what is known of the permissibility of bloodletting, amputating a gangrenous hand, and cauterization with fire. Our calling the lesser harm “harm” is a figurative usage (by naming it after what it would otherwise be); otherwise, in this situation it is not harm at all, but pure good.
Source : Min Thimār al-ʿIlm wa al-Ḥikmah vol.1