The comment was made a short time ago during testimony before the Senate Homeland Security and Gov. Affairs Committee.

"The rising tide of violence we see in the West is clear evidence of the serious threat. As our government takes the fight to groups such as Islamic State of Iraq and ash-Sham (ISIS) and alQa’ida (AQ), we will continue to see operatives disperse and focus more heavily on external operations against the United States, our interests, and our allies. While much of today’s hearing will focus on terrorist threats from Syria and Iraq, it is important to emphasize that the terrorist threat is fluid. Many terrorist groups continue to pose a risk to our security and safety. "

[...]

"In addition to the threat of foreign fighters overseas, the threat from ISIS also contains a domestic component. ISIS utilizes a sophisticated messaging and propaganda capability, which enables it to reach a global audience as it encourages acts of violence wherever its followers are able. The group regularly disseminates high-quality media content on multiple online platforms. ISIS members continue to attempt to recruit and radicalize to violence Homegrown Violent Extremists (HVEs) through social media. The reach and popularity of social media has enabled
HVEs to connect more easily with terrorist organizations, such as ISIS. We assess there is currently an elevated threat of HVE lone offender attacks by ISIS sympathizers, which is especially concerning because mobilized lone offenders present law enforcement with limited opportunities to detect and disrupt their plots. "

Read the full opening statement (PDF):

http://www.hsgac.senate.gov/download/testimony-taylor-2017-12-06

Watch a video of the full hearing:

https://www.hsgac.senate.gov/hearings/adapting-to-defend-the-homeland-against-the-evolving-international-terrorist-threat