Creation of s3 snapshot repository fails with exception

When trying to create an elasticsearch s3 snapshot respository (have the aws plugin installed), I get the following exception:

curl -XPUT 'http://localhost:9200/_snapshot/es_backup' -d '{
"type": "s3",
"settings": {
    "bucket": "ops-backups",
    "region": "us-west",
    "access_key": "<key>",
    "secret_key": "<key>"
    }
}'


[internal:admin/repository/verify]]; nested: RepositoryMissingException[[es_backup] missing];

My s3 bucket permissions look ok...why would it complain about a repository being missing if I'm creating it?