Al Qaeda's No. 2 leader wrote a book published Sunday on militant Islamic Web sites in which he slams radical militants who have disavowed armed struggle and turned their backs on violence.

The 215-page book by Aymen Al Zawahiri is the latest salvo in an intellectual war between the founders of the terror group and the other Islamic militants, many of whom have become disillusioned with homicide bombings and attacks on civilians.

"This message that I present to the reader today is the most difficult, if not the hardest I have written in my life," al-Zawahri wrote in the introduction to "Exonerations," published by al-Sahab, Al Qaeda's media wing.

In it, al-Zawahri rejects a series of "revisions" published by prominent jailed Islamist thinkers that renounce violence.

"It serves the interests of the Crusader-Zionist alliance with the Arab leaders to drug the mujahideen and drag them away from the confrontation," he writes.

The most recent renunciation came in 2007 from Sayed Imam, once a top leader in Egypt's Islamic Jihad group and an associate of Al Zawahiri.

Imam's writings in the 1980s laying an Islamic legal basis for violent action against "infidel" regimes, were highly influential among Al Qaeda militants. But his "revisions" argue that such violence is banned under Islamic law.

Al Zawahiri -- seen by many counterterrorism experts to be Al Qaeda's operational chief, rather than Usama bin Laden -- is believed to play a large role in directing Al Qaeda's strategy on the ground and issues frequent videos an audiotapes, often laying out the network's doctrinal line.

Meanwhile, Al Qaeda released a new video eulogy Sunday of its top Afghanistan strategist on militant Web sites. The video marks the second for Abu Laith al-Libi, showing the slain commander's importance to Al Qaeda.

"Nation of Islam, we pay tribute today to a courageous hero of Islam, an unmatched commander, one of Islam's greatest," eulogized fellow Al Qaeda militant Abu Yahya al-Libi, appearing in front of an image of Abu Laith's battered corpse.

Abu Laith was viewed as a top Al Qaeda strategist in Afghanistan and was one of its highest-profile figures after Usama bin Laden and al Zawahri. He was killed in late January by a missile from a U.S. Predator drone that struck his safe house in Pakistan.