“We mark in these days the passage of nearly 15 years since the blessed invasions in Washington, New York, and Pennsylvania,” the group’s leader Ayman al-Zawahiri said in the video, according to a translation by the SITE Intelligence Group.

Al-Zawahiri also promised that “as long as your crimes continue,” then similar events “will be repeated a thousand times.”

Experts said the message was an attempt to remind the world that al-Qaeda still exists at a time when it is being overshadowed by the Daesh terror organization.

“All of this is very much, ‘Look what we were able to pull off. No one else can do anything like this,’” Nada Bakos, a former CIA officer who tracked al-Qaeda, told ABC News.

Richard Clarke, a former White House counterterrorism adviser, echoed similar views about al-Zawahiri.

"The fact that he is communicating on the anniversary is an attempt by him to remind everybody that he exists and is the nominal head of [al-Qaeda]," Clarke said.

In the video, al-Zawahiri also appeared to be taking a jab at Daesh, saying “real soldiers… do not impose themselves on you as rulers without your acceptance and consultation.”

Clarke said the al-Qaeda leader is probably hiding somewhere in Pakistan and frequently changing his location to avoid being tracked.

The US is marking the 15th anniversary of the 9/11 attacks, which killed nearly 3,000 people and caused about $10 billion in property and infrastructure damage; Press TV reported.

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