US President Donald Trump unveiled on Friday a replacement Air Force One aircraft gifted by Qatar, which he dubbed a "flying White House.""This is considered the world's most luxurious plane," Trump said at a speech inside the plane's hangar, praising the gulf emirate for being "so nice and providing" it.Qatar's gift of the aircraft -- valued in the hundreds of millions of dollars -- has raised ethical, constitutional and security concerns.Trump has previously said it would be "stupid" to reject the gift, while also stoking further concern by saying the plane would eventually be donated to his presidential library.At the unveiling Friday at Joint Base Andrews, outside Washington, Trump praised the workmanship that went into modifying the jet, saying "with the extraordinary devotion of many of you here today, this plane was transformed into a flying White House at a level of luxury that nobody's ever seen before.""When you see it, you won't believe it, actually, the quality of woods, the quality of the materials, the quality of the engines," he added. "And I want to thank the Emir of Qatar."Repeatedly praising the size of the aircraft and its engines, Trump said, "it flies further and faster than any Air Force One."