Although politicians talk about defeating the ISIS, they do not mention the costs or the sacrifices that will be necessary for winning this war. Despite the rhetoric of politicians for political point scoring or for improving their political images, the generals who have fought several wars in the Middle East in recent years are aware of the costs involved in the war. They are well aware of the fact that the ISIS is a ruthless adversary that has changed and adapted to new tactics over the last eighteen month. Despite losing 25% of its conquered they have come up with innovative ways to compensate for their shortcomings.
These adoption tactics include the use of super-sized car bombs which is used in the absence of an air force. The super-sized bombs are made by packing high-density explosives in bulldozers and other heavy equipment and sending this loaded equipment in waves at their targets. They are already using small drones for reconnaissance and might soon be using armed drones which could inflict more damage. They have already used unconventional chemical weapons such as chlorine and mustard gas and when pushed will use more of them to fight their war. They have also adapted to using tunnels and other concealed devices to hide their movements.
The United States has learned the hard way how difficult it is to create a cohesive force that can recapture territory and hold it in Iraq and Syria. Tribal leaders do not trust the Americans and doubt their staying power. They think that the US is more interested in just containment and not complete victory in the war against the ISIS. This thinking is reinforced by US efforts to minimize American casualties which are why they are not committing ground forces in the war effort. They view Afghanistan as an example where despite the presence of Americans for 14 years, they have made no worthwhile impact on the fighting capabilities of the Taliban.
One bitter experience for the Pentagon is the $500 million effort exerted to train and equip the Syrian army that can retake and hold territory from the Islamic State. The effort was wasted because most recruits did not show up and those who did took a severe beating from the ISIS forces. Most of the equipment used by the ISIS has been captured from the Iraqi army who could not stand up against the fierce offensives of the ISIS because they lacked the fighting spirit of soldiers to fight and win a war.