Anthropic issued a statement, stating that access to Mythos and Fable 5 has been partially restored:

Since June 12, we have been working closely with the U.S. government to restore access to Claude Mythos 5 and Fable 5.

Today, the government informed us that Mythos 5—our most powerful cybersecurity model—can be redeployed to a group of U.S. agencies responsible for operating and protecting critical infrastructure.

We are rapidly restoring access for these agencies and will continue working with the government to expand access to Mythos 5, while making Fable 5 available for general use again.