  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.
