Elon Musk on Monday began attacking Apple on Twitter, the social network he bought in October for $44 billion. He offered no details or proof to back up his complaints toward the company.

In a series of tweets, Musk said that Apple had pulled advertising from his site and that it had threatened to remove Twitter from its App Store. Musk didn’t provide details about what elements of advertising Apple had reduced, nor why it might be considering no longer allowing Twitter on its App Store. Some prominent Apple bloggers noted that ads from the iPhone maker had appeared on Twitter next to his tweets complaining about the company’s advertising.

Regardless, Musk tagged Apple CEO Tim Cook in a tweet asking for a response to his complaints.

Apple didn’t immediately respond to a request for comment. Twitter, which no longer appears to have a PR department, also didn’t respond to requests for additional information.

The move marked an escalation by Musk, whose changes to the service since taking over on Oct. 27 appear to have allowed for more hate speech and harassment, prompting many advertisers to pause or end ad spending. Notably, Musk cut half the company’s staff, including many who reportedly tracked foreign influence campaigns and other bad behavior. He’s also begun reinstating accounts of prominent right-wing reactionaries, including Republican and former President Donald Trump, whose account had been permanently suspended after he helped incite the deadly Jan. 6 attack on Capitol Hill in which rioters attempted to overthrow the US government. Musk also reactivated the account of Georgia Republican Rep. Marjorie Taylor Greene, who was kicked off the service in January for spreading disinformation about COVID-19.

Musk didn’t say why he targeted Apple and Cook in more than a dozen tweets Monday, though he did conclude by highlighting the commission of up to 30% that Apple charges developers who sell digital goods, such as new looks for video game characters or content subscriptions, on its service. Musk had previously increased the price of Twitter’s Blue subscription to $8 per month, from $5 per month before he took over, as part of a broader effort to reduce Twitter’s dependence on advertising. The social network relied on advertisers spending money on its service for nearly all its revenue and profit.

To lure more subscribers, Musk offered paying customers access to the company’s blue checkmark badge for their accounts. The move quickly led to confusion as trolls used the system to impersonate large companies, former lawmakers, sports stars and even Musk himself.

Musk’s attacks toward Apple in public appear to mirror his private efforts to call and “berate” the heads of some companies who have curbed ad spending, according to the Financial Times. Other advertisers reportedly responded by reducing their spending to the “bare minimum required so as to avoid further confrontation with the billionaire entrepreneur.”