Earlier quoted context omitted.
Just us-east-1.
But some global services run through us-east-1 - eg Cloudfront is now broken too. So this is also affecting users who don't actually run anything in us-east-1 explicitly (or in the US at all)
You're right that there's definitely some internal coupling though:
> If you want to require HTTPS between viewers and CloudFront, you must change the AWS Region to US East (N. Virginia) in the AWS Certificate Manager console before you request or import a certificate.
From https://docs.aws.amazon.com/AmazonCloudFront/latest/Develope...