Claude Fable 5 returns. The USA lifted the blockade, but it has several issues

The saga surrounding Anthropic’s most powerful models moves forward after almost three weeks. US authorities have lifted export restrictions that had kept Claude Fable 5 and Mythos 5 offline since mid-June, and the company is now bringing both models back. However, the return is accompanied by temporary availability restrictions until July 7th.

The US Secretary of Commerce also commented on the lifting of the ban

Let’s recall that Anthropic introduced Claude Fable 5 and Mythos 5 at the beginning of June – we wrote about both models at their introduction, when the company promised Mythos’s performance with stronger safety features. Just two days later, the company received an export order and had to suspend access to both models for all foreign nationals, including its own employees.

According to authorities, the reason was a method to bypass Fable 5’s safety features. Amazon, as a trusted partner, reportedly pointed out the vulnerability: the model was successfully prompted in one instance to identify a software vulnerability and generate code demonstrating how to exploit it. However, reports also emerged that the shutdown was due to the US government’s concern about alleged unauthorized Chinese group access to the models.

Claude Fable 5 returns. The USA lifted the blockade, but it has several issues Adam Kurfürst News Adam Kurfürst News

A multi-week government review followed. On June 26th, authorities allowed Mythos 5 to be restored for selected domestic organizations, and on June 30th, export restrictions were completely lifted. Anthropic confirmed the return of both models in an announcement; Secretary of Commerce Howard Lutnick stated that his department had worked with the company for two weeks to analyze and approve Fable 5 to ensure government-wide compliance and strengthen the US’s leadership role in artificial intelligence.

What did Anthropic have to do to bring the models back?

The return was not unconditional. Anthropic first had to directly block the technique that Amazon had pointed out. According to its statement, the company trained a new security classifier specifically targeting this method of bypassing safeguards; it claims this classifier detects it in over 99 percent of cases.

At the same time, it expanded its multi-layered approach to security, which combines model training, post-exploitation analysis, and automatic classifiers recognizing potentially dangerous cybersecurity tasks. For Fable 5, it also deliberately increased the classifier’s safety margin, so the model will block even more harmless queries. Security thus took precedence over user convenience – the model, which we described at its introduction as Mythos with a tighter muzzle, received even stricter safeguards.

Beyond technical adjustments, the company committed to closer cooperation with the USA. It promises access to models before release, rapid sharing of information about discovered safeguard breaches, dedicated research teams, and participation in the creation of industry security standards.

There are still several availability issues

Regarding availability, Anthropic will likely not please you. Claude Fable 5 is included in paid plans (Pro, Max, Team, and selected enterprise plans) as standard only until July 7th, and only up to approximately half of the weekly usage limits. After the mentioned date, access switches to a credit model – standard enterprise licenses will require activated credits to work with the model.

So, if you want to create with Fable 5 without extra charges, you should start now. However, it’s fair to admit that the company had already announced a similar step during the model’s introduction. At that time, it stated that it would remove it from regular plans and require credits starting June 23rd. However, the United States government intervened much earlier.

According to Anthropic, the models will return to Amazon Web Services, Google Cloud, and Microsoft Foundry as soon as technically possible.

Claude Fable 5 returns. The USA lifted the blockade, but it has several issues Adam Kurfürst News Adam Kurfürst News

Anthropic thus concludes three weeks during which its most powerful models were unavailable to hundreds of millions of users. The company’s other models functioned without restrictions during the blockade.

Will you return to Claude Fable 5 once it’s fully available again?

Sources: Anthropic, CNBC, CNN