ISIS leader says group is getting stronger in purported new message

ISIS in 2015: How the Militants Fared
ISIS in 2015: How the Militants Fared

ISIS released a new audio message Saturday purportedly from its leader, Abu Bakr al-Baghdadi, mocking the U.S. for not putting combat boots on the ground and criticizing the recently declared Saudi-led Islamic military coalition against terrorism.

Flashpoint Intelligence, a security firm and NBC News partner, verified that the message was released by the group's main media arm via official channels online. NBC News, however, cannot independently verify the authenticity of the audio.

Click through images of Abu Bakr al-Baghdadi:

The terror group's top leader said in the 24-minute clip that ISIS was thriving and that airstrikes by the U.S.-led coalition and Russia in Syria are failing, despite destroying Syrian oil facilities and killing several ISIS leaders in recent weeks.

The U.S.-led alliance doesn't scare ISIS or challenge the group's resolve, said the reclusive al-Baghdadi, who hasn't been heard from publicly since May. He taunted the U.S. for not joining in the fight on the ground, claiming that American troops are too scared to do so.

The message comes amid several setbacks for ISIS. The militant group has come under pressure in Syria and Iraq, where it has declared its self-styled Islamic caliphate on territory that it controls. It lost the Iraqi town of Sinjar last month, as well as areas in Syria at the same time.

Iraqi government troops are also making advances in the ISIS-held city of Ramadi.

Related: Ramadi Assault: Iraqi Forces in Center of ISIS-Held City, Official Says

Earlier this month, Saudi Arabia announced a new 34-member alliance against terrorism that will be based in the kingdom's capital, Riyadh. Iran is not part of the coalition; neither are Iraq and Syria, whose forces are battling to regain ground from ISIS.

Al-Baghdadi warned the nations fighting ISIS that they would pay a price for participating in the war against the group. He also threatened Israel, promising that ISIS is "getting closer" to Israel every day.

He called upon all Muslims to join the fight, claiming it was their Islamic duty.

The U.S. and its allies in Europe have increased airstrikes against the group since the attacks in Paris in November that ISIS took credit for, which killed 130 people.

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