WASHINGTON - Federal authorities have made their first security change directly related to the Boston Marathon attack.

Effective immediately, the Department of Homeland Security has ordered border agents to verify that every international student who arrives in the U.S. has a valid student visa.

The order comes a day after President Barack Obama’s administration acknowledged that Azamat Tazhayakov, one of the students accused of hiding evidence for Dzhokhar Tsarnaev, was allowed to return to the country from Kazakhstan in January without a valid student visa.