United Kingdom defensive cyber operators test their skills and ability to detect enemy presence, expel it, and identify solutions to harden simulated networks alongside international partners from 23 countries during U.S. Cyber Command's CYBER FLAG 21-1 exercise. U.S. Cyber Command’s CYBER FLAG 21-1 exercise, the largest multinational cyber exercise to date, helped more than 200 cyber operators from 23 countries bolster their defensive skills at Joint Base Suffolk, Virginia, from Nov. 15-20. Defensive cyber teams from Canada, Denmark, Estonia, France, Germany, Lithuania, Norway, the Netherlands, Poland, Sweden, the United Kingdom and others participated in CYBER FLAG 21-1.