President Donald Trump grew impatient with how long it was taking to finish new planes to serve as Air Force One, so he started to look for other options.

Air Force Secretary Troy Meink told lawmakers on Thursday that it will “probably” cost the Air Force less than $400 million to retrofit a luxury Qatari plane that President Donald Trump has said he is getting from the Qataris as a gift to use as the new Air Force One.

But the Air Force “believes” it will cost “less than $400 million to retrofit that aircraft,” service secretary Troy Meink said during a House Armed Services Committee hearing Thursday. Meink said the exact cost and details are classified.