It’s not impossible to invade the US. It’s been done several times already, for example 1942 and 1812. Mexico, which shares the same oceanic borders, was invaded by France in 1861 and of course the entirety of the Americas was essentially invaded by colonial settlers.

It’s unlikely for other reasons, but nothing about it is impossible.

Flat cables can be conformant and they still have twisted pairs. Cables just have to meet the physical properties set by the standard.