True or false: Security Groups in AWS cannot be shared across VPCs unless they are peered together.

The statement is false because AWS Security Groups are tied to a specific Virtual Private Cloud (VPC) and cannot be shared across different VPCs, regardless of whether those VPCs are peered. Each VPC has its own set of Security Groups, and even if two VPCs are peered together, the Security Groups remain isolated to their respective VPCs. This isolation is a fundamental principle of VPC design in AWS to maintain security and resource management.

While VPC peering allows communication between VPCs, it does not extend the sharing of Security Groups, which are primarily used to control inbound and outbound traffic for resources within the same VPC. Therefore, the ability to share Security Groups across VPCs, under the conditions of peering or otherwise, does not exist, affirming that the answer is indeed false.