http://www.sciencemag.org/news/2018/06/more-restrictive-us-policy-chinese-graduate-student-visas-raises-alarm

Chinese graduate students in some fields may now receive 1-year visas.

Reversing yet another policy of the previous administration, the U.S. Department of State today began applying tougher restrictions on some Chinese graduate students. The new policy shortens from 5 years to 1 year the duration of visas for those planning to study aviation, robotics, and advanced manufacturing. Although the ostensible reason for the change is to improve national security, U.S. university officials see it as the latest attack on graduate education and the free flow of scientific knowledge.