What, or where, is the city (singular) of the terrible nations (plural)?

Isaiah 25:3 Therefore shall the strong people glorify thee, the city of the terrible nations shall fear thee.

  4 For thou hast been a strength to the poor, a strength to the needy in his distress, a refuge from the storm, a shadow from the heat, when the blast of the terrible ones is as a storm against the wall. 

Are the terrible ones in line 4 from the terrible nations (line 3)?