The kippah and dina d'malchuta dina

Question

If the military forces a Jewish member to remove his kippah because they do not allow head covering, must he comply under dina d'malchuta dina or not? On the one hand, head covering in Judaism is a matter of custom, not law. On the other hand, the rule does seem arbitrary. I know there were cases reported in the press. But what does the halacha say?

(My take from the discussion below: If the government forces you to remove your kippah or else, and your arguments don't sway them, you must remove it under dina d'malchuta dina. Someone correct me if I am wrong.)

Answer 1

As is found at The Virtual Jewish Library on the subject of Dina de Malkhuta Dina, in the section discussing the scope of the laws included in Dina de Malkhuta Dina it quotes the Tashbetz, part 1 No.158 which says:

(1) *ISSUR ("religious prohibitions") AND MONETARY LAW. All agree that the principle does not apply to religious or ritual observances (issur ve-hetter). This was so certain that it was not particularly stressed and is mentioned only in a few sources (Tashbeẓ, pt. 1, no. 158).

So the question revolves around whether wearing a kippah (a head covering) is a religious or ritual observance subject to issur v'hetter.

It is explained in the Piskei Dinim of the Tzemach Tzedek, Vol.1, pp 1-2, that the kippah, as contrasted to the outer hat, which many wear over the kippah when going into public, is required by ritual law. He explains that those places which mention a Jewish man's head being uncovered are referring to the outer hat, which is a Middah Chassidut, not the kippah.

In that context, one would not be required to comply under the principle of Dina de Malchuta Dina.