The US Air Force (USAF) has adopted a new battlefield technique, which Israel has used in the past, as part of its fight against ISIS.
The technique, known as knock operation, is used to get women and children out of threat area when attacking enemies.
USAF has adopted this technique for the first time to minimise civilian casualties as ISIS have been using civilians as human shields.
The US troops used this technique to attack an ISIS financier, who is said to be the major distributor of funds to fighters.
USAF personnel put a Hellfire on top of the building using an air burst so it would not destroy the building, and then knocked on the roof to warn the women and children inside about the attack.
The air force troops carried out the operations after they had ensured women and children were out of the building.
USAF major general Peter E. Gersten said: "We watched him come and go from his house, we watched his supplies, we watched the security that was involved in it.
"And we also watched occasionally a female and her children in and out of the quarters.
"We actually saturated that with intelligence, surveillance and reconnaissance assets, RPAs, to get a pattern of life study.
"And then we formulated a plan to ensure that women and children and the non-combatants were clear of that objective."
Israeli forces have commonly used knock operations to warn civilians when attacking enemies in Gaza.
Image: A model of a Hellfire's components. Photo: courtesy of Stahlkocher.