Point of fact, it started a long time ago. Back in the 1960s, the Soviet Union fielded a Fractional Orbit Bombardment System (FOBS) which put nuclear payloads into orbit. It was a blatant violation of the Outer Space Treaty, but they claimed that since the warhead didn't complete a full rev before reentry, it wasn't a violation. They also fielded an operational coorbital ASAT capability in the 1980s and tested it many times. The system was designed to attack our ISR platforms in LEO. Fortunately, they have not tested that particular system in a long time, but they still retain an operational ASAT capability. The Chinese are publishing papers on microsats and nanosats that can be used to target our military satellites. We have nothing comparable in either case.

The US military is heavily (some say too heavily) dependent on space. If someone manages to degrade or negate some of our space capabilities, it would have an immediate and serious impact on our military operations. We have ample justification to prevent that from happening.