In a new book, former CIA Deputy Director Mike Morell warns that there could be more 9/11-style attacks if anti-terrorism efforts failed to get the Islamic State group under control. Morell said the extremist group -- which is also known as ISIS or ISIL -- was capable of directing more devastating attacks resulting in a wider number of casualties.

Morell's book, “The Great War of Our Time: The CIA's Fight Against Terrorism From Al Qa'ida to ISIS,” was published Tuesday. It is an account of his 33 years of service at the agency. In the book, Morell writes that U.S. efforts have not been enough so far to stop the Islamic State group from recruiting hundreds of Americans. He said that the main reason behind the ineffectiveness of U.S. efforts was that it was a “very hard” thing to do.

In September 2001, Morell was with then-President George W. Bush at an elementary school in Florida when Bush was informed about the 9/11 attack. He also was with President Barack Obama in the White House Situation Room when it was confirmed that special operations forces from the U.S. Navy had killed Osama bin Laden.

Morell said that while some people in the U.S. assumed that the al Qaeda threat was over, intelligence agencies did not share that view. "It was a mistake to think that al Qaeda died along with bin Laden in Abbottabad [Pakistan]," Morell said. The terrorist group lost strength in Pakistan and Afghanistan but developed fresh branches like al Qaeda in the Arabian Peninsula in Yemen.

Morell also criticized deputy national security adviser Ben Rhodes for an email in which he referred to an anti-Islam video as the reason for the deadly Sept. 11, 2012, attack at a U.S. compound in Benghazi, Libya. He said that Rhodes had crossed the line between politics and national security. Rhodes said in the email that the goal was to emphasize that the attack was “rooted in an Internet video, and not a broader failure of policy."

Morell also acknowledged that the so-called Arab Spring protests across North Africa and the Middle East were misinterpreted at first. It was originally believed that the revolutionary wave would undercut al Qaeda. On the contrary, it turned out to be a beneficial recruitment tool for the militant organization. Afterward, U.S. military bases raised the threat level to the highest since 2011. Homeland Security Secretary Jeh Johnson called it “a new phase in the global terrorist threat.” House Homeland Security Chairman Mike McCaul called the present situation “terrorism gone viral.”

Contact the writer: s.mukhopadhyay@ibtimes.com.au