That would not have been pretty, to say the least. Nobody’s saying anything about what the USSR’s anticipated response would be, either. The Bear was very much on the prowl in those days and would not have taken kindly to a nuclear power projection at its back door.
The Chinese and Russians had border clashes in those days. The Russians told Kissinger they were going to preemtively nuke the ChiComs and wanted Washington to green light the operation, which Washington declined to do.