Editor’s note: Vivek Wadhwa, a Triangle-based entrepreneur, is now an executive in residence at Duke University and is a fellow at the Harvard Law School. He writes a column for BusinessWeek online, which granted permission to reprint a portion of his commentary. Wadhwa and fellow researchers have written extensively about engineer graduation rates in the U.S., India and China as well as the ongoing U.S. debate about immigration policies toward engineers and scientists.

DURHAM – Signs with the words "U.S. citizens and permanents only" greeted students at employers’ booths at a recent career fair at Duke University, where I teach.

In previous years only government jobs requiring security clearances were labeled off-limits to international students. Foreign-born engineering graduates told me they were disappointed that employers like General Electric, IBM, and Carmax as well as smaller companies would not even interview them.

Recruiters told me they were frustrated that they could not fill critical positions. They have few options because the visas they need to hire foreign nationals simply aren’t available.

This visa shortage is a problem for U.S. companies that depend on engineers because significantly more foreign-born students than Americans are completing higher degrees in engineering. According to the American Society of Engineering Education (asee.org), foreigners account for nearly 45% of masters-level engineering students and 60% of PhDs.

The result?

Multinationals have little choice but to expand their engineering operations abroad, and smaller businesses that can’t afford to expand overseas are unable to hire the talent they need.

For the remainder of the column, check the BusinessWeek Web link.