The Department of Defense (DoD) has spent more than $17 million on fuel at Scotland’s Glasgow Prestwick Airport since US president Donald Trump’s election, according to federal spending data. That’s a 100% increase from what the DoD spent at Prestwick before Trump’s election, the records show, and about $6 million more than the House Oversight and Reform Committee is now reportedly investigating as a conflict of interest and possible Constitutional violation.

The potential for corruption isn’t hard to spot: The airport is a small but essential transportation center for anyone looking to spend some leisure time at the nearby Trump Turnberry golf resort, which Trump owns. And before Trump took office, the airport struggled financially.

Trump, who broke with tradition and refused to divest from his businesses when he took office, is more conflicted than any other president in US history, government watchdog groups say. During his first two years in office alone, the president has amassed more than 2,300 known conflicts of interest, according to Citizens for Responsibility and Ethics in Washington (CREW), a DC-based nonprofit. The DoD payments to Prestwick appear to be just the latest example.

The Prestwick airport received $0 in payments from DoD between 2008 and 2017. In 2018, however, DoD payments suddenly spiked to $6.5 million, spread out over 359 contracts. So far in 2019, DoD has made 555 payments to Prestwick for more than $10 million—a grand total of $17.2 million.

The Federal Procurement Data System shows that the DOD and Prestwick signed a $5 million agreement for fuel in June 2016, but no payments were made at that time.

“The airport closest to the Trump Turnberry golf course—Glasgow Prestwick Airport has been viewed as integral to the golf course’s financial success, yet it too has lost millions of dollars every year since its purchase by the Scottish government in 2013,” Democratic representatives Elijah Cummings and Jamie Raskin wrote in a June 21 letter to secretary of defense Patrick Shanahan. “Given the president’s continued financial stake in his Scotland golf courses, these reports raise questions.”

Cummings’ office did not reply to an email seeking comment. Trump, for his part, vehemently denied any involvement or wrongdoing.

Details of the arrangement were first revealed by Politico, which noted that the military pays more for fuel at commercial airports than military ones.

A symbiotic relationship

Trump may not “own” Prestwick, but saying he has “nothing to do with” it is untrue. Turnberry and Prestwick formed a partnership in 2014, after which Trump promised to make Prestwick “really successful.”

“We are going to have planes coming in from New York and all over, very high-level planes like Gulfstreams and Bombardiers,” Trump announced at a November 2014 press conference held at the airport.

The House committee launched its inquiry earlier this year after learning that a US Air Force C-17 crew en route to Kuwait from Alaska had been ordered to land at Prestwick to refuel. Normally, C-17s refuel at US air bases in Germany, Italy, or the Azores. Military air crews were allegedly offered free rounds of golf and discounted rooms at Turnberry, an arrangement the Air Force is also now investigating. One crew member, apparently confused about the set up, reportedly texted an acquaintance, saying their daily per diem didn’t cover food and drinks at the Trump resort.

In a statement released Sunday, the Air Force said the service branch doesn’t believe the stays violated government regulations, but is looking into the situation anyway.

“Even when USAF aircrews follow all directives and guidance, we must still be considerate of perceptions of not being good stewards of taxpayer funds that might be created through the appearance of aircrew staying at such locations,” the statement read.

That sweet military money

Trump’s Turnberry resort lost $4.5 million in 2017, the president’s first year in office. Revenue at the club increased by $3 million in 2018, raising the possibility that “the military has helped keep Trump’s Turnberry resort afloat,” reported Politico.

According to Prestwick’s 2016-17 annual report and financial statement, the company “increased military aircraft handling by 37%” between 2013 and 2017. “The company is specifically targeting new military business as a key component of its future development activities,” it says.

The Prestwick filing reveals the facility received its first US military contract in October 2016, the month before Trump was elected. And while operating costs rose accordingly, they were “more than offset by the revenue generated from the [fuel] sales,” it says.

The news that Trump may be profiting personally from taxpayer-funded US military maneuvers follows news that vice president Mike Pence spent two nights at Trump’s Doonbeg golf resort during a recent state visit to Ireland—something the House Oversight Committee is now looking into as well.

Trump again denied having “anything to do with” the vice president’s decision to overnight at his hotel.

The White House did not immediately respond to a request for comment.