WASHINGTON/ANKARA, July 8 (Reuters) - U.S. President Donald Trump said on Wednesday he would leave Turkey on the old presidential plane instead of the recently refurbished aircraft gifted by Qatar, an unexpected change that has prompted renewed scrutiny of the costly and hastily completed renovation.

The flight to Türkiye, the first international flight for the new aircraft, comes at a time of escalating hostilities with Turkey's neighbor Iran.

This change comes after months of scrutiny of this lavish gift, which was supposed to be a temporary replacement, at a time when Boeing is struggling to deliver long-delayed new-generation presidential aircraft.

Critics questioned the cost, security, and speed of the renovation process.

Trump said in a Truth Social post that he would use the old plane "for the sake of old times" to travel to the British Air Force base at Mildenhall while the new plane stops at the same base so that American military personnel stationed there could take a tour of the aircraft.

The new Boeing 747 aircraft was gifted by Qatar to the United States last year, and modifications were made to it by L3 Harris, a contractor for the Department of Defense.

When Trump was asked whether the assassination threat was what prompted him to change planes to leave Türkiye, he did not respond directly but acknowledged the existence of a potential threat.

"I am number one on Iran's assassination list," he told reporters at a press conference following the conclusion of the NATO summit in Ankara. "I don't know. I can't tell you, but I really don't care."

Trump said the Qatari-gifted aircraft would head to two or three large bases in Europe before returning to the United States "so that the soldiers can see it because it's really cool."

The acceptance of that aircraft raised questions. Experts said that modifying the luxury jet required security enhancements, improvements to communications to prevent eavesdropping, and the addition of missile defense capabilities.