The U.S. Air Force is defending an aircrew's decision earlier this year to make a scheduled stop in Scotland and stay at a luxury resort owned by President Donald Trump.

The seven-member crew of a C-17 Globemaster III flying to Kuwait followed all proper procedures and protocols when they stopped at Glasgow's Prestwick Airport and when they booked their stay at Trump's Turnberry resort for a mission in March, the Air Force's top spokesperson told Military.com on Saturday.

"The stopover of a U.S. Air Force C-17 in Glasgow, Scotland, is not unusual," Brig Gen. Ed Thomas said in an email.

"Every two-and-a-half minutes an Air Force transport aircraft takes off or lands somewhere around the globe. As our aircrews serve on these international airlift missions, they follow strict guidelines on contracting for hotel accommodations and all expenditures of taxpayer dollars. In this case, they made reservations through the Defense Travel System and used the closest available and least expensive accommodations to the airfield within the crews' allowable hotel rates."

Related: This C-17 Crew Broke Diplomatic Protocol to Save a Life. Now They're Up for Awards

"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 added.

Politico first reported Friday that the House Committee on Oversight and Reform is investigating the stopovers at Prestwick -- first while en route to Kuwait and then again when returning to the U.S. -- as part of a larger probe into military stays at Trump-owned properties. Politico also reported that the Air Force has spent $11 million on fuel at Prestwick, roughly 20 miles from Turnberry, since October 2017. The crew reportedly could have saved money by refueling at a nearby base such as RAF Lakenheath, U.K., Ramstein Air Base in Germany or Naval Station Rota in Spain.

Lawmakers want to know if U.S. military stays have boosted Turnberry's revenue.

The Tanker Airlift Control Center at Scott Air Force Base in Illinois manages airlift cargo operations around the globe. Air Mobility Command spokesman Col. Damien Pickart said officials are currently working with the air operations center within the Tanker Airlift Control Center to determine how many times military tankers and cargo aircraft have made stops at Prestwick.

"The Trump property -- at $136 a night -- was less expensive than the Marriott property -- $161 a night -- and both were under the per diem rate of $166," Thomas said.

Thomas said the crew, consisting of seven active-duty and Guard crewmembers from Alaska, stayed at Turnberry when en route to Kuwait, "but it doesn't appear the Trump property was used on the return leg."

"A nearby Marriott property was used," Thomas said.

The mission in question began at Joint Base Elmendorf-Richardson, Alaska on March 13, and included stops at Creech Air Force Base, Nevada; Portsmouth International Airport at Pease, New Hampshire, a dual civilian-military airport; Prestwick; and Ali Al Salem Air Base in Kuwait, Thomas said.

The crew returned to Elmendorf on March 19.

Despite the probe into possible irregularities, some cargo and tanker pilots were quick to note that the landings at Prestwick were not unusual.

Aircraft spotters had reported that two Air Force C-130 Hercules were headed for a stop over there on Saturday; Military.com separately spoke with two Air Force pilots who've both stopped at Prestwick in recent months.

"With the Global War on Terror and Operation Inherent Resolve drawing down, countries have become increasingly less accommodating with diplomatic clearances, quiet hour waivers etc. [and] Prestwick has none of those restrictions, and the U.K. allows pretty much blanket diplomatic clearances for us," said an Air Force instructor pilot who flies mobility aircraft.

The instructor pilot provided photos of his aircraft parked on the ramp at Prestwick in May.

He noted that he found it unusual Prestwick is the new "in spot," but added it has given some relief to other bases like Ramstein which typically see a heavy traffic of cargo aircraft and tankers, and Lakenheath, which already hosts an abundance of fighter aircraft.

"Now with Prestwick we can typically cut an East Coast stop -- which saves time -- and we relieve pressure on Ramstein," he said.

"Prestwick is a very, very common stopover and crews only stay at places at or under the lodging rate ... sometimes Turnberry is under the rate, and I wouldn't blame a crew for staying there," added a former active-duty KC-135 pilot who's made a few stops to Prestwick.

The KC-135 pilot said his stops there in recent months were because nearby RAF Mildenhall, U.K., home of the 100th Air Refueling Wing, was too busy to take on more tankers.

"And Ireland is really, really tough to get diplomatic clearance to land through," the KC-135 pilot said.

In April, an Air Force C-17 crew with call sign Reach 445 broke diplomatic protocol to land at Ireland's Shannon airport in order to get expedited medical care for a sailor in critical condition.

For the March Prestwick incident, Thomas said that a local agent on contract with the U.S. government "assisted with the reservations and indicated that there wasn't a room available closer to Prestwick Airport."

"The hotel was 54 minutes from ... Prestwick, but that is not a remarkable distance to travel to receive government-rate lodging," he said.

-- Oriana Pawlyk can be reached at oriana.pawlyk@military.com. Follow her on Twitter at @oriana0214.

Read More: Younger Vets Are on a Mission to Change the American Legion from Within