U.S. President Donald Trump said Wednesday that he secretly switched aircraft in Turkey last month on the advice of the U.S. Secret Service after an alleged Iranian assassination threat raised security concerns. According to reports, Trump was moved from Air Force One to a military aircraft through a catering truck in an effort to conceal his departure. Trump said he believed the plane he ultimately boarded could have been more vulnerable because adversaries might have targeted the aircraft they expected him to use. Although the jet was expected to be used for his return trip, Trump unexpectedly switched to an older Air Force One before leaving Turkey. The secret plane switch came as tensions between the United States and Iran were escalating, adding to concerns surrounding Trump's security during international travel.