According to Press TV, US Assistant Attorney General John Carlin said on Monday witnesses in almost half of cases on Daesh did not report anything to law enforcement authorities until after the charges were made.
He noted the US Justice Department wants the American public to be more proactive about alerting federal authorities about someone showing support for foreign terrorist organizations.
Since 2013, many of the Daesh supporters prosecuted have been charged under "material support" statutes that prohibit supporting designated foreign terrorist groups, according to Reuters.  No organizations based on domestic racist ideology, such as white supremacists have been designated as a terrorist entity.  
If some people support a domestic group should not be prosecuted, Carlin said, because it "runs into our Constitution and our values."
"You're getting close to making illegal ideas," he said.
Last year, the Department of Justice charged 60 people for their nexus, sympathies or support for Daesh, the largest annual figure on record.
The Daesh Takfiri group, which was initially created and funded by the US and its regional allies to destabilize the Middle East region, particularly Syria, has reportedly claimed responsibility for some shootings in the United States.
US warplanes have been conducting airstrikes against Daesh in Iraq since August of 2014. Some Western states have also participated in some of the strikes in Iraq.