studies done on u.s. diplomats and their families who the u.s. government says suffered unexplained health incidents in havana in 2017. a top cuban doctor is calling the methodology and results into question saying, quote, if the control group was not well matched, the differences could be due to uncontrolled factors. for example, he says, for both groups was head concussion history, sports, military service, matched? no evidence is provided of the degree of overlap of patient and control group. the functional connectivity differences, he continues, the second type of measure, can change due to many factors including psychological states. for these measures the overlap in between controls and patient is shown and is very great. the illnesses among american embassy staff of course in 2017 led the trump administration to reverse president obama's diplomatic opening to cuba withdrawing most staff from the u.s. embassy in havana, expelling cuban diplomats from washington. i'm joined now by nbc's josh