WASHINGTON -- President Obama is considering a range of limited military actions against Syria that are designed to "deter and degrade" the ability of President Bashar al-Assad's regime to launch chemical weapons, Pentagon officials said Tuesday.
Although no final decisions have been made, it is likely that the attacks would not be focused on chemical weapons storage sites, even though the Obama administration says the use of chemical weapons by the Syrian military is the trigger for the planned attack. They said any effort to target chemical sites risks an environmental and humanitarian disaster and could open up the sites to raids by militants.
Instead, the American assault would be aimed at military units thought to have carried out chemical attacks, the rockets and artillery that have launched the attacks and the headquarters overseeing the effort, the officials said.
One key question facing Mr. Obama and his advisers is whether such a limited attack would compel a change in tactics of the Assad regime -- which has killed tens of thousands of civilians with conventional weapons -- or weaken Mr. Assad to the point that he would seek a negotiated settlement to Syria's civil war.
An American official familiar with the military planning said that the initial target list has fewer than 50 sites, including air bases where Syria's Russian-made attack helicopters are deployed. The list includes command and control locations as well as a variety of conventional military targets, official said. Like several other military officials contacted for this report, the official agreed to discuss planning options only on condition of anonymity.
Planners said that although suspected chemical weapons depots are seductive targets, they are too risky.
"That is a hairy business," the official said. "Our interest is in keeping the chemical weapons secured. You hit a bunker that holds chemical weapons and all of a sudden you have chemical weapons loose."
Even within the limited mission envisioned for now by the Obama administration, there are some American officials who are urging expanding the target list to include at least military units commanded by Assad family members and loyalists and even presidential compounds.
Officials anticipated that a first round of attacks would be followed by a pause to assess the damage and the regime's response before a potential second wave of strikes would be ordered. With few human intelligence assets on the ground, the inspection of targets after the strike would be conducted by satellite or surveillance aircraft capable of flying above the range of Syria's highly regarded integrated air-defense system.
Officials also cautioned that arguments for a more limited strike included the fear that the refugee flow to American allies Turkey and Jordan -- where the influx already is causing political concern -- would increase. And there are worries that Iranian-backed Hezbollah militants might step up terrorism around the region in retaliation.
Voices across the administration urging no action have all but silenced. But, at the other extreme of military options, a sustained air campaign designed to decapitate the leadership and allow rebels to topple the regime, also has been rejected.
The Air Force maintains a vast fleet of fighter jets and long-range bombers in Europe and the Middle East that are capable of striking Syria, but a range of officials said that, for now, the strike plans were focusing solely on sea-launched Tomahawk cruise missiles and that there was no intention of putting up strike aircraft, which require a large cast of supporting aircraft, including refueling tankers, combat search-and-rescue craft and early warning or electronic jamming planes.
The Navy has traditionally kept two destroyers in the eastern Mediterranean but quietly increased that number to three over recent months. By accelerating the arrival of one replacement and delaying the return of another, the Navy now has four Arleigh Burke-class destroyers within striking range of Syria: the Mahan, Barry, Gravely and Ramage.
Each carries about two dozen Tomahawk cruise missiles, a low-flying, highly accurate weapon that can be launched from safe distances of up to about 1,000 miles and was used to open the conflicts in Afghanistan, Iraq and Libya
Attack submarines also carrying Tomahawks are assumed to be on station in the Mediterranean as well.
But Tomahawk missile strikes, while politically and psychologically significant, can have a starkly limited tactical effect. The weapons are largely fuel-and-guidance systems and carry relatively small high-explosive warheads. One conventional version contains about 260 pounds of explosives, the other carries about 370 pounds. This is less than the explosive power of a single 1,000 pound air-dropped bomb.
The weapons also present certain technical risks. Naval officers and attack planners concede that the missiles are not entirely controllable for elevation near the target, and when they fly slightly high carry the risk of blast effect to structures and people behind or near the targets.
Planners also have difficulty timing the strikes -- which fly from different release points and fly different routes by GPS way points -- so they arrive at their targets simultaneously, which means that the first strikes can alert troops at follow-up targets that attacks are imminent. Thus they are much more effectives against fixed targets, like buildings or infrastructure than against military units or commanders.
This article originally appeared in The New York Times.