Lawmakers and top military officials on Wednesday expressed fears that friction with Russia could someday leave the United States without the power to launch rockets into space. Reliance on a single Russian engine to launch many critical military satellites could come back to haunt the U.S., officials said, if tensions between the two nations continue to rise. “If you consider space a national security priority, then you absolutely have to consider assured access to space a national security priority,” Gen. William Shelton, commander of the Air Force’s space command, testified in a joint Senate committee hearing on Wednesday. “Given that...