WASHINGTON — Concerns about foreign spies and terrorists have prompted the Homeland Security Department to set up its own counterintelligence division and require strict reporting from employees about foreign travel, according to a memo obtained by the Associated Press.

The new directive comes as the federal government increases its counterspy efforts across all agencies and raises the awareness of intelligence vulnerabilities in the private industry as well as in protecting government secrets.

The Homeland Security Department “is vulnerable to adversaries who seek information about our nation’s homeland defense programs, classified or unclassified,” Secretary Michael Chertoff wrote in the August 4 memo to employees obtained by AP.

The agency, formed in 2003 after the terrorist attacks of September 11, 2001, has about 216,000 employees and posts around the world. It includes divisions that protect the country’s borders, develop new radiation detection equipment, study and test infectious diseases, enforce immigration and maritime laws, protect the president and other dignitaries, coordinate disaster response, work to keep terrorists off of airplanes and other transportation, and monitor and prevent cyber-intrusions.

Homeland Security is creating a counterintelligence system now, because there is currently no place for such a function in the department — which was formed by 22 disparate agencies — a senior American government official who requested anonymity because he is not authorized to publicly discuss intelligence, said.

“We are still a relatively young department,” a Homeland Security spokesman, Russ Knocke, said, adding that the memo reflects the department’s maturity over the past five years.

Counterintelligence is an organized effort to block an enemy’s sources of information and access to sensitive material. It can also be used to give misinformation.

In his memo, Mr. Chertoff instructs that employees must tell a special security officer about any planned foreign travel. When the employee returns, the employee should report “any real or possible contacts with foreign intelligence services, terrorists or foreign criminal enterprises.” This reporting, Mr. Chertoff says, will protect department employees who travel abroad.

Mr. Chertoff instructs employees to report suspected espionage behavior. Some examples:

• If someone asks an employee for classified and sensitive information or access to systems.
• If someone asks an employee traveling overseas to bring back an envelope or package.
• If an employee has regular contact with a person suspected of being part of a foreign intelligence service, terrorist group, or foreign criminal enterprise.

While setting up a separate office dedicated to counterintelligence, the concept is not new to the department. In 2005, it published a brochure, “Espionage: How to recognize and report it,” which includes a list of suspicious behaviors.