A more thorough explanation:

A deemed export license is a license required by the United States government for the release of technology or related computer language (source code) to foreign nationals living in the United States. This is because the release of such information to a foreign national is considered an export to the home country of the foreign national.

For example, if a Korean national studying at a university in the United States is given access to computer technology, it is considered an export to Korea, even though the activity took place in the United States. Therefore, many foreign students cannot participate in university research without a deemed export license.

The Department of Commerce's Bureau of Industry and Security (BIS) may classify the deemed export as requiring a license due to national security concerns. The requirement of a deemed export license depends on the relatedness of the technology to defense articles and the United States' relationship with the country to which it is being exported.

License requirements can be found in the Export Administration Regulations (EAR).