So much for holiday spirit. Airbnb and the hotel industry are lashing out at each other, just as the travel season kicks into gear.

On Monday, Airbnb’s head of public policy Josh Meltzer sent a letter to Marriott CEO Arne Sorenson, asking him to explain to Americans “your industry’s habit of taking billions of dollars from taxpayers to subsidize the construction and operation of your hotels.”

The letter, a copy of which CNBC obtained, follows a Fortune interview with Sorenson last week. In it, Sorenson was asked if he thinks Airbnb has become more willing to make concessions or cooperate with regulators.

“I don’t know that I see that they’re more willing to concede,” Sorenson answered. “They’re spending a lot of money on government affairs and they’re playing pretty aggressive. I’ve had letters from Airbnb directly, demanding my response about some charge, I don’t even know what it is, within hours. That’s pretty aggressive, and I’m not going to respond to that.”

It’s the latest phase in a tit-for-tat battle being waged in public and in the press between the Airbnb and hotels. We reached out to Marriott about Monday’s letter but didn’t immediately hear back.

The clash of the Silicon Valley technology disruptor and the old, slow-moving industry has been raging for years and only intensifies as Airbnb gets bigger and more influential. The hotel industry has long claimed that Airbnb skirts laws around taxes and real estate use, while Airbnb has said that hotels are doing everything in their power to protect their turf at the expense of consumers and taxpayers.

Earlier this year, an internal American Hotel & Lodging Association (AHLA) document was leaked, detailing the hotel industry’s plans for limiting the growth of short-term rentals and the platforms that enable them, naming Airbnb as a threat. Marriott, Hilton and Hyatt are members of the group.

Over the summer, an ad campaign backed by the Hotel Association of New York City suggested that short-term rentals could be used to host terrorists. Airbnb countered with an ad featuring interviews of a host claiming that the home-sharing platform helped him earn additional income.

Meltzer wrote in the letter that he read the Fortune interview with interest and said that Sorenson is “unwilling and unable to defend your industry’s longstanding commitment to price gouging consumers, depressing wages and replacing workers with robots.”

Meltzer went on to say that many of Marriott’s hotels are “magnets for bad actors” and he asked Sorensen why a hotel association “has chosen to launch a series of misleading advertisements regarding safety and security.”

The letter also got personal, suggesting that taxpayers have not only subsidized the construction of Marriott’s hotels but also helped fund the almost $12.3 million Sorenson was paid in 2016.