US aircraft conducted 14 air strikes against the ISIL militants near Iraq's largest dam in the past 24 hours, officials said Wednesday, amid ISIL threats to kill a second US journalist.

US drones and fighter jets destroyed or damaged six ISIL’s Humvees, three sites for improvised explosive devices, one mortar tube and two armed trucks, US Central Command said.

The latest airstrikes were in the area of the Mosul Dam and were aimed at helping Iraqi and Kurdish forces create a buffer zone at the key facility.

The strikes, which now total 84 since operations began, have helped Iraqi and Kurdish troops reclaim the dam from the terrorist group.

The militants threatened to kill Sotloff, who is also being held captive, if the U.S. continued to conduct airstrikes.

The United States stood firm Wednesday in its fight against ISIL as President Barack Obama denounced the group as a ``cancer'' threatening the entire region.

``We will be vigilant and we will be relentless,'' Obama said.

The execution of James Foley drew international condemnation. Germany announced it would supply the Kurds in Iraq with weapons to fight the insurgents. Italy's defense minister said the country hopes to contribute machine guns, ammunition and anti-tank rockets. French Foreign Minister Laurent Fabius said the killing showed the true face of this ``caliphate of barbarism.''

In capitals across the Middle East, people also condemned Foley's killing, but also stressed that the ISIL terrorists backed mainly foreign regimes has been committing atrocities against Iraqis and Syrians for years.

Obama's remarks affirmed that the U.S. would not scale back its military posture in Iraq in response to Foley's killing. And at the State Department, spokeswoman Marie Harf did not rule out military operations in Syria to bring those responsible to justice, saying the U.S. ``reserves the right to hold people accountable when they harm Americans. What that looks like going forward, those conversations will be happening.''

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