It poses a threat because the military moves much slower than whatever you’re naively assuming is ubiquitious COMSEC. Many CIA assets over the last twenty years, even some today, sent their communiques through channels protected mostly by Quantum-breakable encryption. If China/Russia got a quantum computer now (hell, probably even 15 years from now), it would be almost immediately followed by volleys of executions of our spies.
It poses a threat because the military moves much slower than whatever you’re naively assuming is ubiquitious COMSEC. Many CIA assets over the last twenty years, even some today, sent their communiques through channels protected mostly by Quantum-breakable encryption. If China/Russia got a quantum computer now (hell, probably even 15 years from now), it would be almost immediately followed by volleys of executions of our spies.