German trade union Verdi has threatened to extend its strikes at Lufthansa if the airline’s executive board does not significantly improve its current wage offer for ground staff. The willingness to strike on the ground has never been as high in the past 20 years as it is now, Verdi negotiator Marvin Reschinsky said on Wednesday at a protest meeting with several hundred participants in front of the Lufthansa administration at Frankfurt Airport. The strike sends a clear signal to the board: “We can go longer if you challenge us to.” Operations at Germany’s largest airport were significantly res…