"Terrorist groups like ISIL have called on people around the world and here in the United States to attack innocent civilians. Their propaganda, their videos, their postings are pervasive and more easily accessible than we want," Obama said at the Treasury Department after his meeting with his national security team.
"This (Orlando shooter) individual appears to have absorbed some of that and during his killing spree, the shooter in Orlando pledged allegiance to ISIL. These lone actors or small cells of terrorists are very hard to detect and very hard to prevent," he said.
Obama said that the government is doing everything it could to stop these kinds of attacks.
"But across our government at every level, federal, state and local, military and civilian, we are doing everything in our power to stop these kinds of attacks. We work to succeed 100 percent of the time. An attacker, as we saw in Orlando, only has to succeed once," he said.
Obama said extremist groups have perverted Islam to justify terrorism.