英文文章求解釋

Science loses as the U.S. tightens visa rules
以下是其中一段:

Part of the reason for the increase in visa denials is that consular officials are being held personally responsible, and possibly criminally liable, if they grant a visa to someone who later commits a terrorist act. Lrying Lerch of the American Physical Society points out that consular officials may not be distinguish a benign field of study from a related but dangerous one and would think it safer to deny visas to most applicants in certain board categories, such as condensed matter physics or biotechnology.


請問當中" consular officials may not be distinguish a benign field of study from a related but dangerous one "是什麼意思?請不要用GOOGLE TRANSLATE等軟件解答,謝謝