The following article by Josh Lederman, Courtney Kube, Abigail WIlliams and Ken Dilanian was posted on the NBC News website September 11, 2018:
The strong suspicion that Russia was behind the alleged attacks is backed by signals intelligence, meaning intercepted communications, say U.S. officials.
WASHINGTON — Intelligence agencies investigating mysterious “attacks” that led to brain injuries in U.S. personnel in Cuba and China consider Russia to be the main suspect, three U.S. officials and two others briefed on the investigation tell NBC News.
The suspicion that Russia is likely behind the alleged attacks is backed up by evidence from communications intercepts, known in the spy world as signals intelligence, amassed during a lengthy and ongoing investigation involving the FBI, the CIA and other U.S. agencies. The officials declined to elaborate on the nature of the intelligence.
The evidence is not yet conclusive enough, however, for the U.S. to formally assign blame to Moscow for incidents that started in late 2016 and have continued in 2018, causing a major rupture in U.S.-Cuba relations.