ISIS flag
ISIS flagReuters

The Islamic State (ISIS) jihadist group on Monday urged its followers to launch attacks in the United States, Europe, Russia, Australia, Iraq, Syria, Iran, and the Philippines during the Islamic holy month of Ramadan.

The call was made in an audio message purporting to come from the spokesman of Islamic State, Abi al-Hassan al-Muhajer, according to Reuters.

The authenticity of the recording could not be independently verified, but the voice was the same as a previous audio message purported to be from the spokesman.

"O lions of Mosul, Raqqa, and Tal Afar, God bless those pure arms and bright faces, charge against the rejectionists and the apostates and fight them with the strength of one man," said the voice in the recording. Rejectionist is a derogatory term used to refer to Shi'ite Muslims.

"To the brethren of faith and belief in Europe, America, Russia, Australia, and others. Your brothers in your land have done well so take them as role models and do as they have done," he added.

ISIS has claimed several recent attacks around the world, including ones in Melbourne, Australia, Tehran, London, and Manchester.

U.S. Secretary of Defense James Mattis recently said that the fight against ISIS has "accelerated" and shifted to "annihilation tactics."

"Our strategy right now is to accelerate the campaign against ISIS. It is a threat to all civilized nations," Mattis told CBS News, adding, "We have already shifted from attrition tactics where we shove them from one position to another in Iraq and Syria, to annihilation tactics where we surround them.”