Those Who Willfully Volunteer To Enlist In Kafir Militaries Are Kufar | Shaykh Ahmad Musā Jibrīl

Give tidings to the hypocrites that there is for them a painful punishment -
Those who take disbelievers as allies instead of the believers. (Sūrah An-Nisā’: 138-139)

O you who have believed, do not take the Jews and the Christians as allies.
They are [in fact] allies of one another. And whoever is an ally to them among
you - then indeed, he is [one] of them. Indeed, Allāh guides not the
wrongdoing people. Sūrah Āl Imrān: 118

O you who have believed, do not take as intimates those other than
yourselves [i.e., believers], for they will not spare you [any] ruin. They wish you would have hardship. Hatred has already appeared from their mouths, andwhat their breasts conceal is greater. We have certainly made clear to you the signs, if you will use reason. Sūrah Āl Imrān: 118