Interior Secretary Ryan Zinke on Friday characterized the controversy surrounding his use of private planes as “a little BS.”

Kicking off his energy speech at the conservative Heritage Foundation, Zinke said: “Before we get started, I’d just like to address, in the words of General Schwarzkopf, ‘a little BS’ on travel” ― a reference to Gen. Norman Schwarzkopf, the Gulf War commander who once memorably described a report as “bovine scatology.”

Zinke said taxpayers “absolutely have the right to know official travel costs” and that the Department of the Interior makes that information available to the public.

“Using tax dollars wisely and ethically is a greatest responsibility and is at the heart of good government,” Zinke said Friday. “And there are times, however, we have to utilize charter services because we often travel in areas and under circumstances that we don’t have other fight options.”

“I fly coach,” he added.

Zinke said he’s used a private plane on three separate occasions. Those trips, he said, included a bipartisan congressional delegation to the Arctic Circle led by Sen. Lisa Murkowski (R-Alaska), chair of the Senate Energy and Natural Resources Committee; a trip to his home state of Montana to meet with Gov. Steve Bullock (D) and speak at the Western Governors Association; and a visit to the U.S. Virgin Islands for the 100th anniversary of the transition of power from Denmark.

Zinke said all of his travel aboard private flights occurred “only after it was determined by multiple career professionals at the department that no commercial options existed to meet the promulgated schedule.”

“Every time I travel, I submit the travel plan to the ethics department that evaluates it line-by-line to make sure that I am above the law,” he said. (A spokesperson for Interior later clarified to HuffPost that Zinke had meant “within the law.”) “And I follow the law.”

He added that he plans to continue flying chartered flights and on military planes when necessary or when invited on official duty.

“I’ll always be honest and upfront about my travel,” he said. “In fact, you can follow me on Twitter. So if you follow me on Twitter, you knew that I traveled by Suburban from Valley Forge this morning.”

As of 3:00 Friday afternoon, there was nothing on Zinke’s official Twitter page about his travels that morning.

On Thursday, it was revealed that Zinke and several staffers had chartered an oil company plane for a flight from Las Vegas to Montana in June, costing taxpayers $12,375. Zinke joins a growing list of Trump administration officials facing backlash over their use of private or military aircraft for government business.

Health and Human Services Secretary Tom Price’s privately chartered airfare has cost taxpayers more than $400,000, according to a series of reports from Politico. On Thursday, Price said he would reimburse the government for his seat on those flights — a day after President Donald Trump said he was “not happy” about Price’s use of private planes.

Treasury Secretary Steven Mnuchin and Environmental Protection Agency Administrator Scott Pruitt have also traveled lavishly. Pruitt’s non-commercial airfare has cost taxpayers over $58,000, according to reports.