China has built mockups in the likeness of a U.S. Navy aircraft carrier and other warships, according to satellite images courtesy of Maxar Technologies.

The U.S. Naval Institute reported the structures have been used for ballistic missile testing.

Tensions have recently risen between the China and the U.S., as the latter country publicly backed Taiwan’s independence as a democracy. China has historically claimed Taiwan as its own, and continues to do so, since the island broke away and began governing itself in 1949.