President Donald Trump speaks while switching planes at US Air Force Base RAF Mildenhall in Suffolk Eastern England, on his way back to Washington from the NATO summit in Ankara, Turkey. (AP/PTI image)US President Donald Trump was secretly moved in an airport catering truck to a smaller military aircraft after boarding Air Force One in Ankara, a covert operation triggered by an Iranian assassination threat, The Washington Post reported Monday.Trump had initially boarded the older, baby-blue Air Force One in front of cameras after attending the Nato summit in Turkey.But after getting on the aircraft, he was secretly shuttled by an airport catering truck to an Air Force C-32A, which then flew him to Britain, the Post reported, citing a US official familiar with the operation and corroborating material it reviewed.The extraordinary security operation came as hostilities with Iran were escalating. Iran borders Turkey, where Trump had travelled for the Nato summit and made his first international trip aboard a newly renovated jet donated by Qatar.The president's unexpected switch from the new aircraft to the older Air Force One before leaving Ankara had raised questions over the security of the Qatari-donated plane.Trump had said on Truth Social before departing Ankara that he would use the older baby-blue Air Force One "for old time's sake" to fly to RAF Mildenhall in Britain, while the new aircraft would also stop at the same base so US service members stationed there could tour it.However, after Trump boarded the older aircraft in front of cameras, he was secretly transferred to the C-32A using an airport catering truck, according to the Post.The deception operation was triggered by a credible threat to Trump, the Post reported. A similar operation took place in 2000, when President Bill Clinton used an unmarked executive jet to fly into Pakistan while sending his formal Air Force One as a decoy.Also read: 'Blood for blood': Iran displays giant billboard with Donald, Melania and Trump children in coffinsOn this occasion, journalists who believed they were travelling with Trump aboard the older Air Force One were advised to keep their window shades in the press cabin closed. The Post reported that some White House staff also believed the president was on board.When reporters later asked Trump why they had been told to keep the shades shut during the flight, he said they were "probably on a dangerous flight." He went onto say: “But if I go, you go. Right?"The C-32A carrying Trump arrived in Britain at around 10:20 p.m., with the older Air Force One and media arriving minutes later, the Post reported. It was not immediately clear how Trump was transferred from the C-32A back to the older Air Force One.Trump's travelling press pool reported that he climbed down the stairs of the older Air Force One at 10:56 p.m. local time. He gave reporters a peace sign but did not walk over to speak with them.He then spent some time greeting US service members before walking towards the new Qatar-donated aircraft.Asked about the revelation that Trump had secretly travelled on a third aircraft, the White House provided a statement from Communications Director Steve Cheung saying the Qatari-donated jet had been fitted with high-level security protocols to protect the president and his staff."As the President has said recently, there are many enemies of America who have their sights on him, and we use every tool at our disposal to address those threats," Cheung said.