Every Chinese expat graduate student here is expected to spy for China.
Students don’t see it as spying rather ‘a Duty to their country’ - and they are taught this.
Check the professors and graduate students backgrounds for military service. The visit rotation between China and the US would support personnel rotation, mission planning, training, checking supplies prior to shipment in containers to the United States, etc.
Just to spin the conspiracy top a bit more, how many Chinese restaurants - staffed entirely by young Chinese men (how many are illegal border crossers?) - are located just outside major military bases, key government and infrastructure facilities/locations?
“When near, seem far away.” Sun Tzu “ The Art of War”