To enable STRICT mTLS at the namespace level, we can use Policy instead of MeshPolicy and define the namespace that it will be applied to. Let's get started:

1. Define mTLS for the istio-lab namespace:

# Script : 07-create-mtls-for-istio-lab-namespace.yaml

apiVersion: authentication.istio.io/v1alpha1
kind: Policy
metadata:
 name: default
 namespace: istio-lab
spec:
 peers:
 - mtls: {}

2. Apply the mTLS security policy at the namespace level:

$ kubectl -n istio-lab apply -f 07-create-mtls-for-istio-lab-namespace.yaml 
policy.authentication.istio.io/default created

Next, we will verify the TLS configuration.