President Donald Trump’s confirmation Sunday that the United States may accept a presidential aircraft gifted from Qatar marked the latest escalation in his clash with Boeing, which is years behind on its government contract to build the new Air Force One.

The Qatari luxury Boeing 747 did not come up during brief remarks celebrating the separate deal between Boeing and Qatar Airways.

The U.S. has officially accepted a luxury jetliner from Qatar as a gift, and slated it to become a new Air Force One. Experts say that overhaul could take years and cost hundreds of millions.