Al Qaeda leader Ayman al-Zawahiri called Wednesday on Muslims to attack U.S., European, Israeli and Russian targets in a speech on the 18th anniversary of the 9/11 terror attacks.

SITE Intelligence Group, which tracks online activity of jihadist groups, reported that in a video released by the militant group, the 68-year-old al-Zawahiri also criticizes "backtrackers" from jihad, referring to former jihadis who changed their views in prison and called the 9/11 attacks unacceptable because innocent civilians were harmed.

1) #alQaeda releases video speech of leader Ayman al-Zawahiri commemorating #911 attacks, titled, “And They Shall Continue to Fight You.” Zawahiri uses #Israel as a launchpad to call for attacks on US, French, British, & other Western interests & alliances https://t.co/2ukRGXZDU4 pic.twitter.com/7jztFV8w8e — Rita Katz (@Rita_Katz) September 11, 2019

"If you want Jihad to be focused solely on military targets, the American military has presence all over the world, from the East to the West," he said. "Your countries are littered with American bases, with all the infidels therein and the corruption they spread."

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The coordinated al Qaeda hijackings on Sept. 11, 2001 killed nearly 3,000 people, when airliners slammed into the World Trade Center and the Pentagon and another crashed in rural Pennsylvania.

Al-Zawahiri's speech was recorded in a 33-minute, 28-second video produced by the group's as-Sahab Media Foundation.

As an indicator of when the speech may have been recorded, al-Zawahiri references President Donald Trump's recognition of the Golan Heights as Israeli territory, which was announced on March 25. He calls on Palestinians to seek "martyrdom" by attacking Israelis with a suicide vest in response.

Al-Zawahiri, an Egyptian, became leader of al Qaeda following the 2011 killing of Osama bin Laden in Abbottabad, Pakistan by U.S. Navy SEALs. He is believed to be hiding somewhere in the Afghanistan-Pakistan border regions. A July report by the U.N. cited reports that he is "in poor health" but provided no details.

Over recent years, al Qaeda has been engaged in fending off competition in jihadi circles from its rival, the Islamic State group. ISIS exploded into prominence by seizing large swaths of Iraq and Syria in 2014, declaring a "caliphate" and extending affiliates in multiple countries across the region.

ISIS's physical "caliphate" was crushed in Iraq and Syria, though its militants are still active and carrying out attacks.

The U.N. report said the "immediate global threat posed by al Qaeda remains unclear" but warned that some would-be ISIS recruits could turn to older organization.

Al Qaeda militants, meanwhile, have taken a lower profile, using regional conflicts in Afghanistan, Syria and Yemen to entrench themselves. The Yemen branch has been the most active, exploiting the chaos of the civil war to carry out bombings, shootings and assassinations in an effort to expand its footprint.

Osama bin Laden's son Hamza bin Laden had been viewed as an eventual heir to the leadership of al-Qaida but was killed in a military operation, U.S. officials have said. Al-Zawahiri lauded Hamza in a 2015 video that appeared on jihadi websites, calling him a "lion from the den of al Qaeda."

The new video was released as President Trump unleashed threats against militants contemplating another attack on America.

"If anyone dares to strike our land, we will respond with the full measure of American power and the iron will of the American spirit and that spirit is unbreakable," Mr. Trump said at the Pentagon.