Quantum Entanglement of Time
Background
In 2088, the theory of quantum entanglement of time is proven, though it remains classified. The law of quantum physics (that which claimed time travel was impossible) were bypassed, by way of entangling qubits of an existing quantum computer from mid-2022. Once entangled, qubits from 2022 were now capable of delivering messages across an infinite time period, so long as a quantum computer existed at both ends of the time period.
While it is theorized that such quantum devices could also produce quantum time traveling, the issue remains: you must have a device at both ends of the time period. And at least in 2095, no such device has been built (we think). Therefore, no quantum time travel can occur to a period earlier than at least 2095.
For now (as of November 2095), only messages can be sent back into time and communication is a one-way street. Such devices are controlled by large governments and limited in use to the specific goal of speeding up the development of such devices so that communication can go both ways. No one completely knows if anyone's still listening on the other end. The only means of confirmation was an obscure scientific publication noting an unusual string of qubit outputs, back in 2022. Since then, no one has been able to discern proof that messages are getting through.
As always, the fear of hijacking the timeline with the uncertainty of the Temporal Paradox hanging out there prevents the future from stopping the Great War. It, however, does not stop the discrete use of bootlegged quantum time messaging devices (if you know how to build one and use it, that is).
Note:
The Black Flea has one such bootleg device, built by the extremely intelligent and precocious Mazie Mandala. In her dissertation, she was the one who proposed the means to bypass the laws of quantum physics and send communications to the past. The New American government took over her research and, for a time, employed her. At the brink of completing her device, she was released without notice and her work confiscated. Word on the street is that she'd been building a parallel device on the sly. Wanted by several government authorities across the universe, she chose to ditch her human shell and change her name to Shoko Matte.
— The Warubozu Usagi