House Intelligence Committee Chairman Mike Rogers (R-Mich.) said late Wednesday that the ability of the Islamic State to draw fighters from Europe, Canada and America poses a major security threat to the United States that must be dealt with immediately.

“This is as dangerous a threat matrix as I have ever seen in my time on the Intel Committee, which is about 10 years,” Rogers said on Fox News Wednesday night. “It is serious. We need to address it.”

While some Republicans have said members of the Islamic State could be trying to sneak into the United States from Mexico to commit acts of terror, Rogers warned that several hundred Canadians are thought to have joined the group, which exposes the U.S. on its northern border.

“Don’t forget about Canada. They believe that there may be as many as 500 Canadians fighting,” he said. “You’re just a car ride away from driving across that border and doing something to the United States.”

But Rogers warned that it’s hard to get an exact count of how many people from western countries are supporting the group, and said he believes the numbers being reported are low.

“Part of the problem is these folks are going with western passports who are going for jihad,” he said. “They’re flying to separate countries and working their way into Syria, so we don’t really know all of these individuals that are there.”

Rogers spoke on the same day it was reported that the West Point was working on a report saying the Islamic State did not just spring up over the last few months, and instead was a group that was known about by the Obama administration for several years. Rogers confirmed that the U.S. had intelligence on the group as it was first taking shape several years ago.

“We watched a pooling of these jihadists in Eastern Syria, and then establish a safe haven,” he said.

Rogers blamed the Obama administration for ignoring warnings from Syria and others in the Middle East, who were asking for help as the Islamic State gained strength.

“When Syria was starting to go, our Arab League partners were calling the United States, they came here, they sent leaders here, they asked Congress, they asked the White House, ‘Hey, we need some help here,’ ” Rogers said.

“And the White House really turned their back on those conversations,” he added. “And the longer it went, the worse it got.”