Tens of thousands of users reported issues using Musk’s platform, formerly known as Twitter, after what appeared to be an earlier outage.

Isik Mater, the director of research at NetBlocks, a company that tracks global internet connectivity, told NBC News that X had suffered intermittent outages since Monday morning. While establishing a DDoS attack with certainty can be difficult, Mater said, Musk’s claim was plausible.

U.S. officials have not determined who was behind an apparent cyberattack on the social media site X that limited access to the platform for thousands of users.