The threat from al Qaeda's senior leadership in Pakistan may have been diminished over the years, a national counterterrorism expert said on "Washington Unplugged" today, but the threat from the terrorist group has grown and evolved in other ways -- including a slightly increased threat from "home grown" terrorists.
"There is a risk of Americans seeing something in the al Qaeda world view," National Counterterrorism Center director Michael Leiter told CBS National Security Analyst Juan Zarate. That risk has increased this year, he said, but he added, "I think it's still too early to say that we have a trend."
Leiter stressed that the Muslim American community is incredibly diverse and a part of every aspect of life in the United States.
"It has been only a tiny, tiny percentage of Americans -- increasingly more this year, but still a tiny percentage of Muslim Americans -- who have for a variety of reasons found appeal in this al Qaeda ideology," he said.
A couple incidents this year, such as the recent arrest of a 19-year-old in Portland, Oregon, "has shown that we have challenges," Leiter said.
"What we have to do in the counterterrorism coummunity is to try and address those root causes and at the same time disrupt those attacks," he continued.
Leiter spoke with Zarate, in a special addition of "Flash Points," after a conference based on the threat of al Qaeda in the Arabian Peninsula (AQAP) at the Center for Strategic and International Studies.
Along with the threat of home grown terrorists, AQAP is another evolving branch of al Qaeda to watch for, he said.
Although al Qaeda remains the leading concern for the United States, other international groups are also investigated.
"We continue to watch Hezbollah... clearly both a political movement within Lebanon, but also the terrorist organization that has killed more Americans than any other, other than al Qaeda," Liether told Zarate. "In addition to Hezbollah, we look at other groups such as the JGK in Turkey."
"Washington Unplugged" airs live daily at 12:30 p.m. ET on CBSNews.com.