During the interview, Brennan was also asked about the threat posed by hackers seeking to infiltrate computer networks.

VOA: standard.2010.02.07

The military said they were in an unauthorized area and suspected of trying to infiltrate Israel.

VOA: standard.2009.12.26

What al-Qaida's greatest strength and its most dangerous capability today is the ability to indoctrinate and infiltrate other established militant groups that have operational capacity."

VOA: standard.2010.05.05