China must boost military spending to prepare for a possible confrontation with the U.S., top generals have said, in an unusual acknowledgment of the risk of a clash between the world’s two largest economies.

The two generals — members of the Central Military Commission led by President Xi Jinping — made the comments during the annual national legislative session in Beijing. CMC Vice Chairman Xu Qiliang, China’s top uniformed officer, said the country needed to brace for a "Thucydides Trap,” an inevitable conflict between a rising power and an established one.

"Facing the ‘Thucydides Trap’ and border disturbances, the military must step up its efforts to improve its capabilities,” Xu said Friday, although the transcript wasn’t released until later. "The most important thing is internal unity and cohesion and improvement of overall capabilities. If you are strong, you will have long-term stability, as well as invincibility.”