The Islamic State is still able to inspire terror attacks around the world, even though U.S. strikes have made it harder for the terrorist group to direct those attacks, National Counterterrorism Center Director Nicholas Rasmussen told a Senate committee on Wednesday.

"One thing that I think that I pointed to this year that was not on the table last year is we have seen a reduction in the ability of ISIS to be able to actually direct and command and control attacks from their safe haven in Iraq and Syria," Rasmussen said at a Senate Homeland Security and Governmental Affairs Committee hearing.

"That's the good news," he said. "The bad news is that they've shown an expanded ability to be able to inspire individuals to take the kinds of actions that we've seen in places, you know, across Europe and potentially even inside the homeland here."

"There's a good news, bad news element to that," Rasmussen continued.

"Obviously, attacks that are driven by an organization under a command and control structure involving all the resources of that organization can be larger and more complex and more lethal," he said. "But that's not to minimize the lethality that comes with a lone individual who may have acquired a firearm, developed an explosive device, so I don't want to overstate the degree to which our threat condition is significantly mitigated by having these inspired plots as opposed to these directed plots."

Rasmussen went on to say that battlefield success might not produce a reduction in terror threats "as quickly as we would like."

The Wednesday hearing was called to address threats to the homeland, and has ranged on a wide number of topics, including cybersecurity, the status of a proposed border wall between the U.S. and Mexico, issues around the Deferred Action for Childhood Arrivals program for illegal immigrants, and the nation's response to the unfolding crisis in Puerto Rico.