Iraqi security forces hold a flag of ISIS they captured during an operation outside Amirli, some 105 miles (170 kilometers) north of Baghdad, Iraq.

A purported audio message by ISIS’s leader said air strikes by Russia and by a U.S.-led coalition had failed to weaken the group.

“Be confident that God will grant victory to those who worship him, and hear the good news that our state is doing well. The more intense the war against it, the purer it becomes and the tougher it gets,” said the message purported to be from Abu Bakr al-Baghdadi.

It was posted on Saturday on Twitter accounts that usually publish ISIS statements.

He also mocks a recently announced Saudi-led Islamic alliance against “terrorism” and warns Israel that “we are getting closer to you” every day.

To Israeli Jews, he says that they “will hide behind trees and stones” from the ISIS.

Al-Baghdadi urges Muslims world over to join the fight, saying it is their Islamic duty to rise up everywhere.

The authenticity of the audio could not be independently confirmed.

Abu Bakr al-Baghdadi at a mosque in the center of Iraq’s second city, Mosul.

Iraqi security forces hold a flag of ISIS they captured during an operation outside Amirli, some 105 miles (170 kilometers) north of Baghdad, Iraq.

Related articles across the web

• Large Majority Of Palestinians Support Violence Against Israeli Jews
• MBTA bans political ads as protesters focus on Israeli-Palestinian conflict
• Palestinian Rams Car Into Crowd of Israelis at Jerusalem Bus Stop
• Thinking the Unthinkable: A Lamentation for the State of Israel - Well, Not Exactly
• Global Pacification, the Matrix of Control and Other Nasties...
• Chess in the Age of ISIS
• Israeli Columnist Applauded at Haaretz Conference for Calling Aliyah a Crime
• Palestinian Rams Car Into Crowd of Israelis at Jerusalem Bus Stop
• Carter thanks servicemembers for their role in fighting Islamic State
• Some Turkish troops pull out from Mosul