The barracks at an airbase in western Germany have been put on lockdown as investigators look into a suspected criminal offence involving a change in the quality of tap water, military officials said on Wednesday. There was evidence of “an attempted or completed illegal intrusion” at the Cologne-Wahn airbase, a Defence Ministry spokesman said. “There is also a suspicion of sabotage.” A spokesman for the German Air Force separately confirmed earlier reports that a hole was discovered in a fence, leading to the suspicion of a break-in on the base. He also said that there were abnormal water leve…