On June 2, U.S. Deputy Secretary of State Tony Blinken told France Inter radio that the U.S.-led air campaign against ISIS had killed 10,000 members in the nine months since the attacks began. This was undoubtedly a salvo in the information campaign against the extremist group, as well as an attempt to downplay the recent loss of Ramadi to the Islamic State. The statistic is interesting, but irrelevant unless it means that the number of fighters in the Islamic State ranks is declining. The count on this score is not encouraging, with indications that ISIS is recruiting enough replacements to balance its losses to air attacks.
The underlying strategy of a campaign focused on reducing enemy numbers is called attrition: kill more fighters than can be replaced, the theory goes, and the opposing side will eventually run out of soldiers to staff its formations. The strategy of attrition, however, has a checkered historical track record, especially when it relies on airpower as the instrument of enemy defeat. The U.S. and South Vietnamese militaries fought for more than a decade to wear down the Viet Cong and the People’s Army of North Vietnam, but hundreds of thousands of enemy deaths did not lead to strategic success. Attacks included heavy use of air power along the Ho Chi Minh Trail and in North and South Vietnam in an attempt to stem the movement of replacements and kill enemy soldiers, to no avail. The fact is that the Communists were waging a total war and were therefore willing to sustain far more casualties than the U.S. military could inflict.
A similar construct is in play in the war against the Islamic State. In Iraq and Syria, the United States has been unwilling to inflict the collateral damage (e.g., civilian casualties) necessary to destroy the Islamic State. Pilots complain of excessive restrictions on targeting that have enabled ISIS to move soldiers and materiel freely across its domains. The air campaign has also been relatively anemic, totaling roughly 15 strikes a day compared with 800 per day during the invasion of Iraq in 2003. The response from the enemy has been predictable: the use of civilians as shields to protect soldiers and installations from attack along with the dispersal of ISIS formations across the cities and deserts of Syria and Iraq.
Of course, ISIS formations would have to mass in order to defend against an attacking force—a lesson learned from the military history of the 20th century, most recently during the air campaign in Kosovo in 1999. But without an adequate partner on the ground in either Iraq or Syria, U.S. airpower has proven ineffective in degrading—much less defeating—the forces of the Islamic State. Absent a change in the ways and means of the strategy to defeat it, ISIS is likely to weather the aerial storm arrayed against it for the foreseeable future.