The admission process of international students has been always had ambiguity. It also had positive and negative associations attached to it. keeping national security of the US in mind.
Taking positive aspects into account. We can see how foreign students and scholars take part in various research projects. In which they get to know and appreciate many aspects of American culture and values. When they go back to their home countries, it results in increasing global goodwill about the US.
This becomes more important. When these graduates and scholars get prestigious positions in their country. Or even become leaders and persons of influence within their polity.
On the other side, some international students and scholars take part in activities. That is against the interests of the American communities. These activities include but are not limited to participation in terrorism to espionage. Some of them act as a “sleeper agent” for those organizations, put into place to be used. When needed by their controllers, or on some specific event.
The percentage of those types of immigrants is small. When compared to the metrics. But it takes only a small intent to cause serious harm to the United States and to create a national tragedy.
Other international students or scholars could be professional intelligence officers, who are working as a spy after getting retired from armed forces.
Even more, students who are not related to any government organization, work undercover. They get any kind of useful information on sensitive projects and research work conducted in the institutions.
Policies for international students are a major exploitable point of U.S. national security. It has two main aspects.
On one hand, there has been a de facto weakening of America’s ability. In training, educating, and hiring STEM Graduates into the U.S. government and other institutions.

This is because local Universities recognize the monetary benefits of bringing international students. So, they become a priority over national students. Fees, the cost of stay and other expenses are paid in full amount by the government.
It feels quite heart wrenching to see local institutes, which gave admissions to students holding the nationalities of countries. They belong from hostile or are global competitors of the United States of America.
On the other hand, it is a major risk for the United States in bringing all these students, from hostile countries.
There is no regulation on the number, place of origin, or courses and research studies of foreign students and exchange scholars. Many students are being used by the governments to engage in spying and theft of important trade and defense secrets.
Apart from that, some legislative actions are being done to limit the number of visas granted. To those students pursuing degrees in the STEM courses. Strong legal action will be taken against exchange scholars and students, who took part in some spying activity, working against the interests of national security.