The director, James M. Murray, was appointed by President Donald J. Trump in 2019 and is departing after nearly three decades with the agency.
In a regulatory filing on Friday, Mr. Musk said Twitter was in “material breach” of the acquisition agreement.
The e-commerce giant planned to build an airport cargo center, hire 1,000 workers and invest hundreds of millions of dollars over 20 years.
The suit, involving girls ages 8 and 9, claims TikTok knew or should have known that its product was “addictive” and was directing children to dangerous content.
Numerous federal agencies agree that widely promoted falsehoods threaten the nation’s security. Doing something about them is another matter.
Twitter’s lawsuit is part of a broadening battle between the biggest tech companies and governments around the world over who gets to control information and how.