Comments from Delta CEO Ed Bastian this week seem to allege that the co-opetition between CrowdStrike and Microsoft may have played a role in the massive July 19 outage.

For years, Microsoft and CrowdStrike have had what can only be described as a strange—and strained—relationship.

This was true long before the global IT outage two weeks ago, wherein their technologies interacted in such an utterly disagreeable way that much of modern society ground to a halt for a day or more. Countless airline passengers, medical patients and banking customers were among those impacted, not to mention some of the largest corporations in the world. One of which, we are told, lost a half-billion dollars.

As you may have known or guessed, that corporation was Delta Air Lines, whose CEO Ed Bastian has now made it clear he has no intentions of moving forward without seeking compensation.

[Related: CrowdStrike Outage Fallout: 5 New Developments]

Bastian’s interview with CNBC included his comment that Delta has “no choice” but to bring legal action against CrowdStrike over the incident. (“We are aware of the reporting, but have no knowledge of a lawsuit and have no further comment,” CrowdStrike said in a statement responding to the Bastian interview.)

Reportedly, Microsoft is likewise in Delta’s sights for a forthcoming suit.

That is, while CrowdStrike has accepted responsibility for the outage—the security vendor says its buggy verification system was the culprit—Bastian and co. seem to think Microsoft also dropped the ball. He even offered a little hint about this during the televised interview.

“People don’t realize Microsoft and CrowdStrike are the top two competitors around cyber with each other. So they don’t necessarily partner at the same level that we need them to,” he said, referring to fierce rivalry between the vendors in endpoint security and other segments. (CRN has reached out to Microsoft for comment.)

While Bastian didn’t go into further specifics on the matter, I can’t help but think he’s reacting at least in part to the war of words that has been going on between CrowdStrike and Microsoft executives for several years now.

Co-opetition is obviously a standard part of today’s tech industry. But the back-and-forth between these two companies has been unusually public and hostile, especially for companies that are at the same time so important to each other (CrowdStrike is responsible for protecting thousands of Microsoft customers, and derives much of its business from this fact).

As just the latest example of their outwardly tense relationship: A month prior to the outage, CrowdStrike CEO George Kurtz slammed Microsoft over its latest security gaffe in an interview with me — ultimately concluding that “time and time again, Microsoft has put profits and features over security.”

Maybe these sorts of fighting words haven’t had any bearing on the way CrowdStrike and Microsoft’s teams have interacted behind the scenes, and thus are not to be connected in any way to what happened on July 19.

But Bastian seems to think something was amiss in the CrowdStrike-Microsoft relationship in the run-up to July 19.

Or at least, that’s what Delta is planning to soon argue in court.