The leader of Al Qaeda marked the 12th anniversary of the September 11 terrorist attacks by asking Muslims to commit more attacks on Americans, CBS reported.

Ayman al-Zawahri, primary leader of the terrorist group, released a new audio message on Friday that was posted on jihadi blogs after being produced by their media company, as-Sahab.

"To keep up the hemorrhage in America's security and military spending, we need to keep the Unites States on a constant state of alert about where and when the next strike will blow," he said in the video. "Keeping America on its guards only requires from us scattered strikes here and there." 

His audio message emphasized "lone wolf" attacks in addition to ones as severe as 9/11 to punish the U.S. for "the continuous war on Islam and Muslims." He also asked Muslims to kidnap Americans to gain leverage in negotiations to release Muslims imprisoned in the West. 

John Miller, senior news correspondent at CBS and former FBI official, suggested al-Zawahri's message seems desperate. 

"He's looking at the Boston marathon bombing, which was a terrorist attack but rather small. He's seen the profound effect it's had on Boston and he wants more," Miller said. "To me, the tacit admission is that al Qaeda does not feel it's in the position, organizationally, do what it used to do, which is organize and launch it themselves." 

"I think he lacks the charisma of bin Laden," he added. "He's an Egyptian pediatrician and he's a smart guy, but his message hasn't resonated." 

Although al-Zawahri's previous messages released on the anniversary of 9/11 included images and footage of the attacks, this one did not include any clips. 

After threatening more attacks on U.S. soil during a 17-minute rant, the rest of the hour-and-12-minute video focuses on other topics pertaining to Islamist movements in the Middle East. al-Zawahri condemned the Egyptian military for overthrowing President Mohammed Morsi although he partly blamed the Muslim Brotherhood for not properly ruling "in accordance to the Islamic Sharia" law.

"Mohammed Morsi was not ruling according to the Sharia and abided by all the security treaties with America as well as by the peace and normalization treaty with Israel," he said.

The last message al-Zawahri released was in July when he promised to get revenge on the U.S. for the treatment of inmates at Guantanamo Bay, many of which are from Al Qaeda.