• Elon Musk is criticizing Apple's App Store policies, and other tech CEOs have voiced support.

• Musk, who has 119 million Twitter followers, brings new attention to Apple's tight control of iOS apps.

• Apple successfully defended its policies in previous court battles, but Musk poses a new headache.

Tim Cook can't be happy that Elon Musk has decided to wage  a "war" against Apple.

Musk is a powerful, vocal person with powerful, vocal friends, and his continued criticism promises to shine a very public light on how much power Apple has over Twitter and other app-based businesses — a headache for a company that has been forced to defend its policies in court and before Congress in the past.

Musk laid out his main critique bluntly in a tweet reply to fellow "PayPal Mafia" member David Sacks: that Apple, as well as Google, "effectively control access to most of the Internet via their app stores."

If Apple, for instance, decides that it doesn't approve of a certain app, it can yank it from the App Store — essentially vanishing it from a good chunk of the internet, or at least the nearly 50% of the US market that uses an iPhone.

It did just this with the app Parler, which Apple removed following the January 6 Capitol siege. Parler beefed up its moderation policies and Apple let it back onto the App Store, but the company described it as a "PG" version with "enhanced threat-and-incitement reporting tools." Now, Musk is loosening Twitter's content-moderation policies and tech observers say Apple could pull it from the App Store, too. An Apple spokesperson did not immediately respond to Insider's request for comment on Musk's statements ahead of publication.

Musk says that's simply too much power for one company to wield. And while other companies — most notably, Fortnite maker Epic Games — have sued Apple, the company has stood firm: It retains its role as a gatekeeper.

But with Musk making noise, will more people take notice?

Already, Florida Gov. Ron DeSantis, said Tuesday that Congress should act if Twitter is ever banned from the App Store.