The Islamic State is vowing retribution should U.S. airstrikes hit their militants. 

According to Reuters, a newly released video by the Islamic State shows a picture of an American man who had been beheaded in Iraq during the initial U.S. invasion with a caption that translated into English reads, "we will drown all of you in blood."

The Islamic State has focused on its goal of establishing a caliphate by seizing land in Iraq in Syria before launching any potential attacks on the West. Osama Bin Laden famously warned of the risks of establishing the caliphate too early, writing that an Islamic State could have the adverse affect of dividing the Sunni population. 

While Sunnis alienated by the Shia government of Nouri al-Maliki have actually helped the Islamic State's swift march through the northern part of the country, many suggest that defeating the Islamic State will only come with Sunni support

In the meantime U.S. airstrikes have helped Kurdish and Iraqi Army forces take back some territory in the northern part of the country that had been seized by ISIL. On Monday, the Iraqis regained control of the strategically important Mosul Dam, which has previously been referred to as "the most dangerous dam in the world." 

Part of the U.S. offensive in Iraq involves targeting millions of dollars of its own equipment given to the Iraqi Army during the U.S. occupation and later seized by Islamic State militants after they seized two Iraqi military bases this summer. According to Reuters, some of the hardware the U.S. is attempting to destroy includes M1 Abrams tanks (about $6 million per), Mine-Resistant Ambush Protected Vehicles (about $1 million per), and 53 M198 Howitzer cannons ($527,337 per).

Reuters estimates that the U.S. spends somewhere between $84,000 and $104,000 to destroy between $1 and $12 million of its own military hardware per airstrike.