fence impregnable

(іст.) неприступна перешкода (напр. моря, що оточують Велику Британію)

sit on the fence / be on the fence (in the Ukraine war)

impregnable line

barbed wire fence

double apron fence

double concertina fence

double-apron fence

single concertina fence

single strand fence

sit on the fence

surveillance fence

trestle apron fence

triple concertina fence

knock-down fence

break-down fence

jagged picket fence

radar picket fence

straddle the fence