A C-17 crew comprising both Air National Guard and active-duty airmen stayed at President Donald Trump’s posh Turnberry golf resort in Scotland during a trip earlier this year to deliver supplies to Kuwait, Politco reports.

Multiple sources told Politico the crew stayed at Turnberry in April, and one crew member noted that their per diem allowance did not cover the cost of food and drinks.

Now, the House Oversight Committee is investigating why the Globemaster III made the unusual layover and who authorized it.

Politico reports that the inquiry is part of a broader investigation into U.S. military expenditures at and around Trump Turnberry Resort.

“According to a letter the panel sent to the Pentagon in June, the military has spent $11 million on fuel at the Prestwick Airport — the closest airport to Trump Turnberry — since October 2017, fuel that would be cheaper if purchased at a U.S. military base,” Politico reports. “The letter also cites a Guardian report that the airport provided cut-rate rooms and free rounds of golf at Turnberry for U.S. military members.”

In a statement Saturday evening, Air Force spokesman Brig. Gen. Ed Thomas said that the C-17′s stop in Glasgow was not out of the ordinary.

The aircrew made reservations at Turnberry through the Defense Travel System, Thomas said, and it was the least expensive and closest available property, within their allowable hotel rates, to the airfield. Air crews on the service’s frequent international airlift missions “follow strict guidelines on contracting for hotel accommodations and all expenditures of taxpayer dollars,” Thomas said.

"While we are still reviewing the trip records, we have found nothing that falls outside the guidelines associated with selecting stopover airports on travel routes and hotel accommodations for crew rest,” Thomas said.

Both the golf course and the airport near Glasgow were running up debts prior to the U.S. military’s involvement, so the incidents call into question whether the U.S. military has been keeping them afloat, Politico reported.

In February 2018, the Guardian reported that the Air Force is conducting frontline missions out of Glasgow Prestwick Airport, “and its executives have highlighted its close relations with President Trump’s nearby resort at Turnberry to promote its bid to become a spaceport backed by the U.S. government.”

The Pentagon has so far ignored lawmakers’ requests for documents as they conduct the probe, Politico reported.

Thomas said in the email that a local agent who was contracted to the government and helped with these reservations indicated that, while the Turnberry hotel was 54 miles away from the Prestwick Airport, there was not a closer room available. Thomas said 54 miles is not a particularly unusual distance to travel to receive government rate lodging.

The Trump hotel’s nightly rate of $136 was less than the $161 rate of a nearby Marriott hotel the same aircrew stayed at during their return flight, Thomas said. The maximum per diem rate was $166, Thomas said.

The seven-airman crew, which included both active-duty airmen and Air National Guardsmen from Alaska, departed Joint Base Elmendorf-Richardson in Alaska March 13, Thomas said. It flew first to Creech Air Force Base in Nevada, then to Pease International Airport in New Hampshire, before flying to Prestwick.

The flight then proceeded to Ali Al Salem Air Base in Kuwait, and then retraced its steps back to Elmendorf, where it arrived March 19. Thomas said the stops were scheduled to provide the optimum distances between them, and for other practical reasons such as availability of fuel.