"Here in the United States there have been more terrorist cases this year involving homegrown jihadists than any full year since 9/11," McCaul stated during a Commitee hearing on threats to national security.
McCaul noted that the Islamic State terrorist group alone has inspired or directed 17 terror plots in the United States since early 2014.
It has also been linked, he added, to more than 60 plots against targets in Western countries ranging from Canada to Australia.
Earlier in October, Assistant Attorney General John Carlin announced that the Unites States has created a new position at the Department of Justice to help US attorneys combat domestic terrorism more effectively.
The Islamic State is a militant group in control of large areas of Syria and Iraq. The group is notorious for its brutality and human rights violations, as well as for recruiting throughout the world via social networks.