- A new video is released of a French hostage, taken in Algeria
- The U.S. says it won't respond to "every new piece of ISIL propaganda"
- Australia, France and UK speak out against new ISIS threats
- ISIS spokesman: Kill disbelievers, whether they are American or French
Western allies vowed a tough fight against ISIS on Monday after the terrorist group called for attacks against those countries.
"This call for the murder of civilians along with the execution of hostages and mass slaughters testifies once again, if necessary, of the terrorists' cruelty and justifies a tireless fight," French Interior Minister Bernard Cazeneuve said in a statement.
"We are giving our law enforcement and security agencies the resources and legislative powers they need to keep Australia and Australians as safe as possible," the Australian Prime Minister's office said.
The UK Home Office called the message "propaganda" and called for Internet providers to pull it down.
"The Government will not tolerate the existence of online terrorist and extremist propaganda," the office said.
The U.S. response was more muted. "We're not going to respond publicly to every new piece of ISIL propaganda," the National Security Council said. The Islamist terrorist group calling itself the "Islamic State" is also known as ISIS and ISIL.
"It just shows they are a threat," a senior defense official said.
"The United States remains vigilant about threats to U.S. citizens at home and abroad. Ensuring the safety of our citizens is a top priority. Our security posture will continue to respond appropriately to protect the American people," a senior State Department official said.
"These latest comments from ISIL demonstrate once again that it remains more interested in pursuing its own violent and nihilistic goals rather than advancing any productive agenda for the people of Iraq or Syria. Beyond that, we don't intend to get in a back and forth with ISIL, or any other terrorist group, regarding its propaganda."
These countries, part of the coalition taking on ISIS, were responding to a new audio recording in which a senior ISIS leader, for the first time, explicitly called for attacks in the United States and on the home soil of Western allies.
ISIS leader: Behead Westerners
The leader specifically called for lone-wolf attacks in the United States and France -- two countries that have been conducting airstrikes against ISIS in Iraq.
The U.S. State Department had no comment to CNN when asked about the message Sunday night.
"Hinder those who want to harm your brothers," the ISIS spokesman said. "The best thing you can do is to strive to your best and kill any disbeliever, whether he be French, American or from any of their allies."
Civilians should not be exempt from brutality, he said. "Do not ask for anyone's advice and do not seek anyone's verdict. Kill the disbeliever whether he is civilian or military, for they have the same ruling. Both of them are disbelievers. Both of them are considered to be waging war."
"Oh Americans, and oh Europeans, the Islamic State did not initiate a war against you, as your governments and media try to make you believe," the ISIS spokesman added. "It is you who started the transgression against us, and thus you deserve blame and you will pay a great price."
He gave specifics on how to attack Westerners: "Rig the roads with explosives for them. Attack their bases. Raid their homes. Cut off their heads. Do not let them feel secure. Hunt them wherever they may be. Turn their worldly life into fear and fire. Remove their families from their homes and thereafter blow up their homes."
Al Qaeda has called for similar attacks in the past. But given ISIS' radical support base, which believes ISIS leaders are the rightful sovereign leaders of all Muslims worldwide, the ISIS pronouncement carries more weight.
France: We are not afraid
"Their threats will not deter our determination to end their acts of violence and rescue persecuted populations," Cazeneuve said.
"France is not afraid" because it is "not the first time we have been threatened by terrorist groups that attack our values of tolerance, humanism, respect for human rights and democracy," he added.
"France is not afraid because it does not intend to give in to terrorist traps. It knows that unity, serenity and citizens' vigilance is the best answer that can be enforced against them. France is not afraid because it is prepared to respond to its threats."
Separately on Monday, the French government said one of its citizens was abducted in a mountainous region of Algeria. A video claim of responsibility was later released by the Islamist militant group, Jund al-Khilafa fi Ard al-Jazaair, or Soldiers of the Caliphate in Algeria, whose leader recently pledged allegiance to ISIS.
The group threatens to kill the hostage in the video, which shows the captive on camera.
"We hereby warn (French President Francois) Hollande, the head of the criminal French State, to stop attacking the Islamic State within 24 hours from this statement, otherwise your citizen will be slaughtered. If you want his life, you must make an official announcement to end your aggression on the Islamic State. You are here being warned," says a masked man.
Australia: 'Be confident'
The Australian Prime Minister's office released a statement Monday saying it is treating the ISIS statement as genuine.
"We are giving our law enforcement and security agencies the resources and legislative powers they need to keep Australia and Australians as safe as possible," the office said.
But it also fired back at the radical militant group.
ISIS "will claim that our involvement in this international effort is the reason they are targeting us, but these people do not attack us for what we do, but for who we are and how we live," the statement said.
"Australians should continue to be confident to go about their daily lives as normal."