The morning of Sept. 11 began like any other. That was true in New York City in 2001, before terrorists struck the World Trade Center. And it was true in Washington in 2018, when President Trump began his day not with a somber remembrance of those killed 17 years prior but with a tweet excoriating the investigation into Russian interference in the 2016 election.

We're used to Trump waking up early and tweeting whatever's on his mind. We're also used to those things being on his mind because he's just seen them on television. That appears to be the case with Trump's tweet on Tuesday morning. Matthew Gertz, who tracks Trump's early-morning tweets, noticed that the content of the message matched a segment on Fox Business that aired Monday night. Trump, an avid DVR user, was probably watching it on delay this morning.

That Fox Business was airing a segment on the Russia investigation — seemingly not a subject that overlaps much with the business world — is also not much of a surprise. The network often discusses political news of the day, sprinkling in more updates on the markets than the Fox News network but otherwise holding a consistent political line.

Trump tweets most commonly between the hours of 7 a.m. and 10 a.m. Since Oct. 1, 2017, 30 percent of his tweets have been sent in those hours, which overlap with the 6 a.m. to 9 a.m. broadcast time of “Fox & Friends” (especially considering that Trump watches that show on delay, too).

How influential is Trump's Fox-watching? Consider three people who have been the subject of Trump's angry tweets: former FBI deputy director Andrew McCabe, former FBI agent Peter Strzok and Justice Department official Bruce Ohr. Trump's tweets about the three (and Strzok's romantic partner, former FBI lawyer Lisa Page) have tracked heavily with Fox News's and Fox Business's coverage of the individuals.

The most obvious exception on the chart above is that first mention of McCabe. That was a retweet by Trump of someone quoting the head of Judicial Watch — the conservative organization that's driven much of Fox News's coverage of the Russia investigation.

The peak of network coverage came with McCabe's firing in mid-March. Trump's most mentions of any of the group came with the Justice Department inspector general's report that was released in June.

Much, but not all, of Trump's tweeting about the three does follow news developments related to them. But consider coverage of Peter Strzok by cable network. Fox News has been much more likely to cover incremental new developments related to Strzok than CNN or MSNBC. Trump's tweets about Strzok (and Page) have a density that reflects Fox's coverage much more than other networks.

We're not exactly reading tea leaves here. On Tuesday morning, Trump made obvious that his tweet about Strzok was related to what he was watching on television by including Fox News's Twitter handle in his tweet.

Trump has mentioned Fox on Twitter more than 250 times since he was inaugurated. Often, those tweets are citations of Fox as the source of whatever he's tweeting about.

Between his first tweet and the one above, addressing a much-hyped Fox News report that has already drawn scrutiny, Trump's Twitter account did include a tweet about the 9/11 attacks.

It was a retweet of his social media director, one of the few other people with access to Trump's account. Whether it was Trump's decision to send that tweet is not currently known.