Given the nature of the regime's passive defensive capabilities, a powerful U.S. operation of at least several rounds may be necessary.
As Washington continues to deliberate its response to the Syrian regime's August 21 chemical attacks in Damascus, the Assad regime has taken the opportunity to institute passive defensive measures as a means of protecting high-value assets and forces from outside military action. In general, such measures can include dispersing key units, moving headquarters to densely populated civilian areas, concealing weapons systems, and similar efforts. The regime began implementing some of these steps soon after the chemical attacks and continues to do so.
In the event of a U.S. strike, passive measures would comprise only part of Syria's defensive response -- the regime would also actively defend its airspace with surface-to-air missiles and antiaircraft artillery. Yet these active measures are unlikely to have much effect on U.S. forces, and reporting from inside Syria suggests that regime military personnel have low confidence in them. Passive defenses may in fact be more effective, and their early implementation suggests that a U.S. strike needs to be robust if Washington hopes to deter the regime and degrade its capabilities.
OBJECTIVES OF PASSIVE DEFENSE
By the time a U.S. strike takes place -- assuming it actually does -- the Syrian regime will have had several weeks to prepare its defenses. In-depth public discussion of the means and methods of attack, the long history of similar U.S. and allied operations, and the opportunity to observe President Obama's handling of the conflict have probably given the regime a reasonable perspective on what an attack will look like: namely, a raid of limited scope and duration, not a campaign.
The regime likely hopes that passive defensive measures can reduce the direct effects of a strike, make the United States appear weak, ineffectual, and even irresponsible, and produce civilian casualties and other collateral damage that could be exploited for propaganda purposes. According to this line of thinking, sufficiently bad results could dispel any support for additional strikes -- if not in the United States, then at least among lukewarm supporters elsewhere.
The regime is somewhat constrained in its defensive preparations by the need to continue prosecuting the war. It must keep units deployed in the field, secure key installations and facilities, and exercise command and control over its forces. Yet even this requirement carries some advantages: the regime's ground forces were widely distributed around the country well before the chemical attacks, not concentrated in a few easily targeted locations, and its command and control have been decentralized to a degree, with regional command centers believed to be dictating the day-to-day operations of forces in their areas of responsibility.
TYPES OF PASSIVE DEFENSE
The regime could take three broad types of passive defensive measures in the event of an attack: movement, denial, and deception. First, it could move forces and functions in several ways. It could disperse combat forces to reduce the effects of outside strikes, spreading equipment and personnel more widely while keeping them in roughly the same area of operation. It could also redeploy units to different areas, playing a shell game by moving key assets (e.g., surface-to-surface missiles) from place to place to stay ahead of U.S. intelligence. In addition, headquarters, communications capabilities, and other functions could be moved to locations with which they are not normally associated or where the risk of collateral damage could deter strikes. Although all of these measures would have some disruptive effects on the Syrian military and its conduct of the war, they could reduce its vulnerability to attack. Their effectiveness in mitigating damage would depend on the quality of U.S. intelligence and how quickly targeting could be adjusted.
Second, the regime could use denial to defend its forces. In military terms, denial can be as simple as putting equipment under roof or tree cover or within densely built-up areas. If U.S. intelligence cannot find the equipment, it cannot be hit except by luck. Such measures can be bolstered by reducing electronic emissions and other signatures. The regime could also use its large system of bunkers to shield equipment and personnel. Bunkers can be defeated by certain kinds of munitions, but the types of weapons often employed in limited U.S. strikes (e.g., Tomahawk cruise missiles) cannot carry these munitions. Even if the requisite weapons were used, targeting bunkers puts a premium on knowing which facilities are active and who or what is in them -- another major intelligence issue.
The regime could also place forces and functions in civilian areas and facilities, making them more difficult to find and, more important, putting civilians at risk. This could be augmented by deploying human shields to facilities the regime does not want to move out of, such as major command-and-control facilities.
The third category of passive defensive measures is deception. This can entail the use of camouflage, decoys, and false electronic signals to misdirect attacks. It can also involve generating false effects (blast damage, fires, and smoke) or disseminating false communication signals and messages (e.g., fake videos). These actions could be used to influence the U.S. military's battle damage assessment (BDA) process and exaggerate civilian casualties and collateral damage.
All of these measures are relatively simple to implement, can work synergistically, and are as old as warfare itself. Some have reportedly already been carried out, including dispersal, movement of forces and functions, movement into civilian areas, and deployment of human shields. Those measures that increase the risk to civilians could play to President Obama's sensitivities.
COPING WITH PASSIVE DEFENSE
As mentioned above, much of the U.S. military's ability to offset these measures depends on quality intelligence collection and analysis, and the time to do both. The United States has significant capabilities for both real-time and persistent intelligence collection against enemy forces. If these capabilities were employed in support of a Syria strike, the regime's ability to move its forces without detection would be reduced. Timely and accurate intelligence could also reduce -- though not eliminate -- the risk of collateral damage.
Much also depends on precision of execution. Weapons have to hit their intended targets, especially if there is only one round of strikes. If there is more than one round -- probably a necessary condition for success despite presumably heavy pressure to limit the operation -- the ability to adjust on the fly to updated regime measures would be important. Syrian forces cannot be expected to stand still if attacked. Using enough weapons to provide good target coverage and high levels of damage would be important. The smaller the target sets and the fewer the weapons employed, the more vulnerable the plan would be to passive measures.
BDA and restrike/follow-on strike capabilities must also be in place beforehand. Again, a single round of strikes is unlikely to inflict enough damage, so additional rounds would probably be necessary. In addition, opportunities to strike at new targets may present themselves as the regime reacts to the operation.
Another crucial element is preparing an information strategy to deal with civilian casualties and collateral damage, whether actual or falsified. Even if nothing goes wrong from the U.S. standpoint, the regime is sure to claim widespread loss of civilian life and destruction to civilian facilities, producing "evidence" (videos, eyewitnesses, bodies) to make its case. The United States will need to be ready with a more convincing story, backing it up with credible information and releasing it in a timely manner.
Although passive defensive measures cannot defeat a U.S. strike, they could reduce its effectiveness and complicate its execution. Some intended targets will be missed, and some unintended or undesirable ones will probably be hit. In a campaign, adjustments could be made based on enemy reactions, U.S. intelligence assessments, and the U.S. military's ability to target adaptively. Yet in a limited strike of one or two rounds, such adjustments are much more circumscribed, and Syria's passive measures would create complications and frictions in the BDA and restrike processes. The regime likely believes that these measures will help it ride out an attack and perhaps give it some opportunities to avoid further attacks. It may well be right.
This argues for a powerful U.S. operation of at least several rounds -- a campaign that provides sufficient opportunity to strike, do the BDA, restrike as needed, and exploit targeting opportunities. The temptation to quickly declare "all bombs on target" should be resisted.
Jeffrey White is a Defense Fellow at The Washington Institute and a former senior defense intelligence officer.