The next US administration should rectify "costly and consequential" federal policies that have damaged American universities' ability to attract top academic talent from around the globe, urged Lee C. Bollinger, president of Columbia University.

In an open letter to US President-elect Joe Biden on Thursday, Bollinger says thousands of international students are unable to return to the United States.

"Or, if they are able to gain entry, they face onerous restrictions that threaten their ability to pursue their academic careers."

Bollinger says, "Of greatest concern, there has been a sustained assault against the vibrant exchange with the international community."

It's a grave mistake to turn international students away or hinder their ranks, says Bollinger who sees international students as being "utterly foundational to our pursuit of excellence in American higher education".

In the past four years, the federal government has erected barriers to foreign students coming to the US, cut the length of their stay, and curbed their ability to work here after completing their studies, Bollinger says.

Hence, "our ability to attract the greatest academic and scientific talents from around the globe, whether in the form of promising students or gifted faculty members" has been eroded, he says, urging Biden to take action against this as soon as possible after his inauguration in January.

Bollinger calls for reforms, including expanding H-1B visas to restore postgraduate opportunities for international students and reducing the backlog of requested visa renewals and applications.

He also asks that the next administration allows sufficient duration of stay for international students to complete degree programs, end paranoia of Chinese students and work with Congress to address long-term challenges facing international students and faculty.

Prior to the COVID-19 pandemic, over 1 million international students came to the US each year to study, according to Bollinger.