AWS Cert Mgr - How to create root CA certificate?

In the below option from AWS Certificate manager, I have an option to create subordinate CA but not root CA,

Goal is to first create root CA certificate and then create sub-ordinate CA that is signed(issued) by root CA's private key.

Documentation also talks about creating subordinate CA but not about root CA

Does AWS certification manager allow creating private root CA? if yes, How to create private root CA with AWS Certification manager?

Solution

This changed today. ACM Private CA now supports creating roots and subordinates.