A U.S. military airstrike Sunday struck an Al Qaeda leadership and training facility in northern Syria where militants were “plotting external attacks” against American citizens, officials said.

The U.S. Central Command said Monday in a statement the strike occurred near the northern province of Aleppo.

The British-based Syrian Observatory for Human Rights, an opposition-linked war monitor, said Monday the strike killed eight members of the Al Qaeda-linked Horas al-Din, which is Arabic for “Guardians of Religion.”

THOUSANDS MOURN AL QAEDA-LINKED TERRORIST - DUBBED 'INDIA'S MOST WANTED' MILITANT - KILLED IN KASHMIR

The Observatory said the dead included six commanders: two Algerians, two Tunisians, an Egyptian and a Syrian.

Al Qaeda-linked militants control wide swaths of northern Syria, mostly in Idlib province, the last major rebel stronghold in the war-torn country.

U.S. military officials said northern Syria remains a “safe haven” for Al Qaeda leaders actively coordinating terrorist attacks.

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“With our allies and partners, we will continue to target [ISIS] and Al Qaeda to prevent both groups from using Syria as a safe haven,” the statement said.

It’s been more than two years since the U.S. military struck al Qaeda fighters inside Syria.

The last known strike was launched in mid-March 2017 in northwest Syria’s Aleppo Province killing dozens of fighters, days before the U.S. military launched cruise missiles targeting an airfield in Syria linked to a chemical weapons attack the Trump administration blamed on Syria President Bashar al-Assad.

Fox News' Lucas Tomlinson and the Associated Press contributed to this report.