Microwave, hell, even GPS-based time sources exist.
If I can sync ALL my [important] servers across the globe to the EXACT same time (under 2 microseconds variance in the last 7 days), and all that on the off-the-shelf hardware, surely a NATION can devise something better?
If I can sync ALL my [important] servers across the globe to the EXACT same time (under 2 microseconds variance in the last 7 days), and all that on the off-the-shelf hardware, surely a NATION can devise something better?