LB,
Geiger counters at every point of entry to every Satanic country.
That ignores existing smuggling routes that avoid established checkpoints thus your thought sounds good on paper but is unworkable as there are other crossing points and methods.
Remember the US Open Border policy of the Biden Administration and how millions of un-vetted people flooded into the country?
Look at the problems the UK is experiencing with the boat people and other folks sneaking across the borders.
How hard would it be to smuggle a "Dirty Bomb" into either Country?
What's worse....has it already happened and we just do not know about it?