If there was still any doubt about Jay Leno feuding with NBC executives — and his asking for it when it comes to threats from Jimmy Fallon — well, Leno pretty much declared battle straight from the top on last night's Tonight Show. Watch the monologue here; there are snakes involved.

It only took a simple one-liner — classic Leno in its soft but obvious bite — to confirm what everyone was thinking, that this internal war is getting ugly, public, and begging for a replacement. "You know the whole legend of St. Patrick, right?" Leno said in the monologue"St. Patrick drove all the snakes out of Ireland — and then they came to the United States and became NBC executives. It's a fascinating story." Yup, things aren't going well in the land of the peacock.

Leno seemed to be responding to a weekend report from The New York Times' Bill Carter, who wrote that Leno and NBC Entertainment president Robert Greenblatt recently participated in an "exchange of pointed e-mails," concerning jokes Leno made about NBC's ratings performance. Which is news, but, you know, touchy — Greenblatt is pretty much in charge of getting good ratings. That would appear to make him the "snake" in question. NBC's performance woes of late are no secret. But apparently Leno crossed Greenblatt's invisible line on The Tonight Show February 28 with a quick series of jokes: 

Leno called NBC "Cinco de Ratings" because they're behind Univision, joked that The Biggest Loser is the channel's "new motto," and then capped it all off with NBC calling Manti Te'o to help find some viewers. 

The very next day, The Hollywood Reporter's Kim Masters reported NBC was fast-tracking plans to replace Leno before is contract expires at the end of 2014. Fallon was going to get the call-up from the Late Show into Carson's old spot as early as summer 2014. An announcement would come in May, and then a year-long "Goodbye, Leno" lovefest would follow. Fallon and Leno did make some awkward jokes about potential succession at the Golden Globes:

The logic behind the switch, according to Masters, was to try and fend off ABC's Jimmy Kimmel, who recently moved his show to the same time slot as The Tonight Show. NBC executives are worried because Kimmel was inching closer to Leno in the coveted 18-34 demographic. Which is all fine and dandy — they're free to do what they want — except Leno is still one of NBC's only consistant ratings winners, and the most viewed late-night host in any demographic. Kimmel only beats Leno in the 18-49 demographic (by a slim margin) when Leno takes the week off. It would make sense if NBC got rid of Leno because he's insanely expensive, but to say Kimmel poses some kind of threat is slightly ridiculous. Leno's still the top dog, or at least he's got a right to claim dominance in insidery, not-that-funny jokes.

That doesn't mean Leno won't get the boot early, though. There's some very obvious tension between Leno and NBC right now, and if this sort of thing continues, the Leno-to-Fallon handoff could very well arrive even sooner than first reported. NBC hasn't taken a beating like this from their Tonight Show host since Conan's last week on the job. We all know how that turned out.