Models supported by the Bedrock RetrieveAndGenerate API?

In following the instructions to create a RAG-backed search experience I get the error below if I don't use a Claude model. Is Claude the only model supported by the RetrieveAndGenerate API?

So, this works:

    const command = new RetrieveAndGenerateCommand({
        input: {
            text: input
        },
        retrieveAndGenerateConfiguration: {
            type: 'KNOWLEDGE_BASE',
            knowledgeBaseConfiguration: {
                knowledgeBaseId: kbId,
                  modelArn: 'arn:aws:bedrock:us-east-1::foundation-model/anthropic.claude-v2'
              }
        }
    });

But this..

    const command = new RetrieveAndGenerateCommand({
        input: {
            text: input
        },
        retrieveAndGenerateConfiguration: {
            type: 'KNOWLEDGE_BASE',
            knowledgeBaseConfiguration: {
                knowledgeBaseId: kbId,
                   modelArn: 'arn:aws:bedrock:us-east-1::foundation-model/meta.llama2-70b-chat-v1'
              }
        }
    });

...throws the following error:

 model arn provided is not supported. Please check your configuration and retry the request.

I have access to both models.

Expected?

If so, are there plans to support other LLMs in this API?