There has been much recent discussion of the criticality of the 5G infrastructure, and whether certain vendors should be able to supply 5G equipment. The key issue appears to be about trust, namely to what degree the security and reliability properties of 5G equipment and systems need to be trusted, and by whom, and how the necessary level of trust might be obtained. In this paper, by considering existing examples such as the Internet, the possible need for trust is examined in a systematic way, and possible routes to gaining trust are described. The issues that arise when a security and/or reliability failure actually occurs are also discussed. The paper concludes with a discussion of possible future ways of enabling all parties to gain the assurances they need in a cost-effective and harmonised way.