In many use cases, 5G can be a segment of a more complex end-to-end solution. In our paper, we discuss the existing 5G security mechanisms related to the connection of trusted and untrusted non-3GPP access networks (wireless and wired), 5G roaming, and the 3GPP approach to support Uncrewed Aerial Services, which provides authentication between the mobile terminal and an external server. The identified use cases show the need and for reusing 5G security mechanisms beyond the 5G network domain. In that context we discuss the options for end-to-end defence in-depth security provisioning in multi-domain networks, and we present two approaches to providing end-to-end defence-in-depth. We propose the alignment of security policies of multiple domains based on security proxies or the use the multi-domain network slices to solve the problem.