India, July 9 -- US President Donald Trump flew home from the NATO summit in Turkey aboard an ageing Air Force One rather than the sleek, Qatari-gifted jet he had arrived in days earlier, a surprise last-minute swap that unfolded hours after the United States launched fresh strikes on Iran and reignited scrutiny of the new plane's security capabilities.

Trump offered little explanation for the switch beyond nostalgia, telling reporters he would be flying home on the legacy aircraft "for old time's sake."

Pressed by a reporter on whether the change was tied to renewed threats from Iran, Trump did not directly answer, instead repeating a warning he has made in recent days about his own personal risk.

"I'm No. 1 on the kill list for Iran,...