PARIS (AP) — American Airlines is buying 50 of Airbus’ newest long-range plane in a big boost for the just-launched A321XLR.

Airbus and the world’s largest airline announced the deal Wednesday at the Paris Air Show, upgrading a previous order for A321neo jets to the A321XLR. No price tag was put on the contract but it is likely worth billions of dollars.

Airbus launched the A321XLR program Monday, a long-range version of its popular single-aisle A320 range, and has already signed several customers for the yet-to-be-built plane.

The move heightens pressure on Boeing, which is studying a new jet dubbed New Midsize Airplane, or NMA, that would be a similar size to the A321XLR. The American Airlines deal could give Boeing more incentive to push ahead with the NMA.