The FBI is warning American college students studying in foreign countries to stay on high alert. They can sometimes be targeted for spy work without their knowledge.

FOX News reported.

US college students studying abroad prime targets for espionage activity, FBI warns

The FBI has issued a stern warning to U.S. college students studying abroad: Beware of foreign intelligence officers who are discreetly targeting young, often naive Americans for espionage activities.

Glenn Shriver seemed like any other adventure-seeking college student — embarking on a study abroad program to China in 2004 while majoring in international affairs at Grand Valley State University in Allendale, Michigan.

The cash-strapped college junior from Jenison, Mich., soon became an easy target of Chinese intelligence officers, who first paid him to write political papers in what seemed like a benign job. The People’s Republic of China officers then befriended Shriver — sometimes meeting him in swanky hotel penthouses — and asked that he consider applying for U.S. government jobs.

Shriver complied, spending the next few years applying for jobs with the U.S. government — in particular, with the CIA and State Department — and receiving a total of $70,000 in exchange for doing so. When his scheme to provide the Chinese with classified information was uncovered in 2010, Shriver, now 32, pleaded guilty and was sentenced to four years in prison.