Orbital ATK Inc. has sparked national security concerns among White House officials by shifting to foreign purchases of an essential chemical the company and other Pentagon contractors use to power U.S. missiles and rockets.

Orbital ATK is seeking to remain competitive in the fast-changing aerospace industry partly through its acquisition of more than one million pounds of low-priced ammonium perchlorate from a French joint venture of Safran SA and Airbus SE in the past year.

In behind-the-scenes clashes, high-ranking trade, military and space advisers to President Donald Trump have voiced opposition to Orbital’s purchase as part of company cost-cutting initiatives, according to industry and government officials familiar with the details.

The propellant is available at a higher price from a sole domestic source, closely held American Pacific Corp., controlled by Utah’s billionaire Huntsman family, which founded multinational chemical powerhouse Huntsman Corp. Low sales volume and high fixed costs have made the company vulnerable to less-expensive competitors.

The material is a vital oxidizer that controls how quickly and with what power solid rocket motors burn. It is used in everything from missiles carried under the wings of Air Force fighters to the largest, nuclear-tipped missiles buried in silos or hidden beneath the seas aboard Navy submarines.