Reports of problems with X started early Monday, with users in Asia, Europe, and North America saying they could not access the platform, according to the Downdetector tracking site.

"There was (still is) a massive cyberattack against X," Musk said in a post on the platform, which was working sporadically as the day wore on.

The SpaceX and Tesla boss also blamed a cyberattack, although he provided no evidence, for crashing the site last year when an interview with Donald Trump was about to be streamed on it.

Musk shared a post from an account called DogeDesigner suggesting that the latest cyberattack was another burst of animosity towards him, in line with recent protests against the so-called Department of Government Efficiency (DOGE) that he leads and vandalization of Tesla facilities.

Musk speculated that such an attack would take tremendous resources, and that it was the work of a country or large coordinated group.

During an interview on Fox Business, he alleged that computers used in the attack appeared to have digital addresses in the Ukraine area and that X was still trying to figure out exactly what happened.

Cybersecurity experts say that it is difficult to assess the situation without being able to see into X operations, but the duration of the trouble is a sign of an attack.

"It's cyberwar hitting at full force," said Chad Cragle of cyber defense platform Deepwatch.

"With Musk in the spotlight and political tensions at a peak, these attacks bear all the indicators of nation-state aggression."

- Ax wielding -

Trump responded last week to growing criticism over unprecedented cuts to the US government overseen by his billionaire advisor Musk, saying they should be carefully targeted.

"We say the 'scalpel' rather than the 'hatchet,'" Trump posted on his social media platform Truth Social.

The president's message represents the first significant move to rein in the power accorded to Musk, as DOGE works toward gutting federal staffing and spending.

DOGE's cost-cutting campaign has faced increasing resistance on multiple fronts, including court rulings and some pressure from lawmakers.

Trump confirmed that he had convened his cabinet to deliver the message that they, not Musk, were in charge of their departments.

Outages on the X social media platform left tens of thousands of users unable to access the site intermittently over the course of hours, according to monitors.

At the peak, more than 40,000 people reported outages, the site said.

After Musk bought Twitter for $44 billion in late 2022, the majority of employees left or were fired, raising concerns about whether staffing was in place to keep the platform safe and stable.

Under his ownership, the platform has experienced technical issues and reinstated accounts of right-wing conspiracy theorists and Trump.

Advocacy groups say misinformation has flourished on X under Musk, who has come under fire for spreading it to his huge online audience.