Mark F. Giuliano assistant director of the FBI's Counterterrorism Division, painted a troubling portrait of the jihadist threat in a Thursday afternoon address. Speaking to the Washington Institute for Near East Policy, Giuliano focused on two particular dangers: al-Qaida and homegrown Islamist terror.

Giuliano said the most serious threat to the American homeland comes from al-Qaida in the Arabian Peninsula (AQAP). Leaders of the group like Anwar al-Awlaki and Samir Khan "have published articles on the Internet detailing their intent to strike the United States," he said.

Key AQAP leaders "were born or educated in the United States and understand our culture, our limitations, our security protocols and our vulnerabilities. They use this understanding to develop and refine new tactics and techniques to defeat our security measures and attack us," Giuliano said. AQAP realizes "the importance and value of reaching English-speaking audiences and are using the group's marketing skills to inspire individuals to attack within the homeland. In many cases, they are attempting to provide them with the knowledge to do so, without having to travel or train abroad."

He added that the two most recent AQAP attempts to strike the U.S. – the attempted Christmas Day 2009 bombing of Northwest Flight 253 and the attempted bombings in October 2010 of air cargo flights traveling from Yemen to the United States – illustrate the diversity of the threat. "In each instance, AQAP was able to recruit a small group of individuals committed to attacking the United States and whose backgrounds were less likely to trigger security scrutiny," Giuliano said. "Additionally, AQAP claimed a significant victory for each attack due to both the fear they created and the economic impact expended by the United States and others to screen passengers and packages compared to the small expenditure on their part. "

The homegrown threat manifests itself in two different ways. Individuals inside the United States such as Fort Hood shooter Nidal Hasan; Hosam Smadi, who pled guilty to attempting to bomb a Dallas skyscraper; and Khalid Aldawsari, who allegedly plotted to bomb the home of former President George W. Bush, "become radicalized and motivated to conduct attacks against the homeland," Giuliano said.

In other cases, like those of Najibullah Zazi and Faisal Shahzad, individuals "become radicalized in the United States and travel or attempt to travel overseas to obtain training and return to the United States or to join and fight with groups overseas."

Read the full speech here.