This morning Donald Trump lashed out at Boeing claiming its budget for the successor to the current Air Force One is wildly overpriced.

Boeing is building a brand new 747 Air Force One for future presidents, but costs are out of control, more than $4 billion. Cancel order! — Donald J. Trump (@realDonaldTrump) December 6, 2016

What prompted this?

Boeing responded by saying that it is currently under contract for only $170 million, though Boeing’s statement suggests the current contract only covers an initial investigatory stage of the construction of the airplane. “We are currently under contract for $170 million to help determine the capabilities of these complex military aircraft that serve the unique requirements of the President of the United States,” Boeing said in a statement.

According to Politico, the current Pentagon budget for not one but two planes is $1.65 billion.

It certainly seems that the number is off. But why did this have Trump’s attention this morning? This seems like a relatively obscure issue given the range of things Trump is now working on. TPM Reader TC notes that The Chicago Tribune published this article about 20 minutes before Trump tweeted. That is, at least according to the 7:30 AM central time timestamp; Trump tweeted at 8:52 AM eastern.

The Tribune articles by Robert Reed starts like this …

The brain trust at Boeing, among the city’s largest companies and a global aerospace and defense powerhouse, must cringe every time President-elect Donald Trump riffs on foreign policy, especially when it comes to dealing with China.

Boeing has a high percentage of its manufacturing in the US. But it is highly dependent on exports, especially to China.

The article recounts a speech Boeing CEO Dennis Muilenburg gave before the Illinois Manufacturers’ Association on Friday in which he was mildly critical of Trump’s plans both for the Export-Import Bank and more protectionist trade policies. The Tribune story wasn’t the first time the speech was reported on. The Puget Sound Business Journal wrote up the speech on Friday. But a Google search (which is obviously an imperfect measure) suggests that the Tribune story was the only published mention of the speech in the last 24 hours prior to Trump’s tweet. It seems at least plausible that the Tribune story was the first or one of the first reports of the speech Trump or his team saw.

Again, this is pure inference. We have no proof that the speech or the write-up triggered the tweet. We don’t know that Trump or anyone close to him was aware of the speech at all. But I think it is reasonable to say that this is an odd thing to tweet about out of the blue, especially with numbers that appear to be fictitious. Something must have prompted this. This seems like a good candidate for what that ‘something’ was.