The Central Intelligence Agency has rejected suspicions that a years-long string of mysterious health ailments affecting U.S. diplomatic personnel abroad is the result of a coordinated attack by a global power. In a statement quoted by The Washington Post on Thursday, a spokesman for the agency said: “We assess it is unlikely that a foreign actor, including Russia, is conducting a sustained, worldwide campaign harming U.S. personnel with a weapon or mechanism.” The official noted that a foreign power could still be behind some of the cases that cannot be explained by a medical condition, but not as part of a coordinated campaign. The finding is a blow to U.S. health officials who’ve long warned of Russia as the likely culprit for the “anomalous health incidents” that have been reported among diplomats in Havana, Paris, Geneva, and around the world. The unexplained phenomena have left some U.S. personnel suffering strange neurological issues and cognitive impairment, and some have reportedly suffered brain damage.