Let that be done by the EU once Trump decides to leave NATO. (/s of course, no one can ever invade the US, and their decisions are theirs as long as they do not seek conflict with other countries!).

The Netherlands also does this. They create 'Bicycle streets' or 'fietsstraten' where drivers have to give priority to and aren't allowed to pass cyclists. Way better than this and doesn't require too much construction in principle.