BEIRUT (CBS News/CBSDC/AP) — The leader of the Islamic State of Iraq and Syria (ISIS) has purportedly said the extremist group will fight to the last man, in a strident audio recording released Thursday that was his first public statement since a U.S.-led alliance launched airstrikes against his fighters in Iraq and Syria.

The statement was posted online six days after Iraqi officials told The Associated Press that Abu Bakr al-Baghdadi was wounded in an airstrike in Iraq. It was not clear whether the recording was made before or after the incident.

In the 17-minute recording, al-Baghdadi vowed to fight the “crusader campaign” to the bitter end and called for “volcanoes of jihad.”

“God has ordered us to fight,” he said. “For that reason the soldiers of the Islamic State are fighting… they will never leave fighting, even if only one soldier remains. They will never leave fighting, because they reject humiliation.”

The recording, released on social media networks, appeared authentic, and the voice appeared to match that in previous recordings released by the group, though it has not been independently confirmed.

The self-styled caliph called on Muslims to wage holy war everywhere, and to attack and kill “apostates” in Saudi Arabia and Yemen specifically. An earlier audio recording from al-Baghdadi is believed to have inspired militants in Algeria to kill and behead a French national.

CBS News correspondent Elizabeth Palmer reports that the U.S.-led airstrikes have slowed the militants’ speedy advance and helped Kurdish peshmerga soldiers in the north hold their ground.

In the town of Kobani, they even pushed ISIS back, but that was an exception.

In spite of the U.S. military spending an average of $8.3 million a day on this operation, ISIS hasn’t given up much — if any — territory. It still controls a huge wedge — more than 10,000 square miles — of Iraq and Syria, including major roads and border crossings.

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