WASHINGTON - The expected U.S. missile strike against Syria would be aimed at forces linked to chemical weapons as well as broader military targets, according to military officials and defense analysts.
Broad command and control and artillery and missile launchers, which can fire conventional or chemical weapons, would likely be targeted, analysts said.
The Pentagon would probably avoid targeting stockpiles, which could send toxic gases into the air and cause civilian casualties.
"We don't want to hit actual chemical weapons because of the dangers," said Jeffrey White, an analyst at the Washington Institute for Near East Policy and a former Defense Intelligence Agency official
The Pentagon said Tuesday they are prepared to launch an attack if ordered to do so by President Obama.
"We are ready to go," Defense Secretary Chuck Hagel said.
The U.S. Navy's 6th Fleet has positioned four destroyers in the eastern Mediterranean, each capable of carrying up to 90 Tomahawk cruise missiles, though most carry less during normal deployments.
The U.S. Navy fired 212 Tomahawks during the bombing campaign that helped topple Libya's Moammar Gadhafi in 2011.
The campaign against Syria is expected to be more limited, aimed not at decapitating the regime but in sending a message and deterring further use of chemical weapons.
The United States has weapons that can penetrate thick walls and incinerate chemicals inside, said Ralf Trapp, a France-based chemical weapons disarmament expert.
But even with specially designed munitions cruise missiles are not a good way to strike chemical weapons since they are fired from miles away.
"This gets risky if you are doing it long range with cruise missiles," said Kenneth Pollack, an analyst at the Saban Center for Middle East Policy at the Brookings Institution.
Targeting convoys or open ammunition pits would be even more dangerous, since the odds of releasing toxic fumes would be even greater, Trapp said.
Assad's regime has regularly moved its chemical stockpiles around, presumably to keep them out of rebel hands.
"We know for a fact it is moving from time to time," Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, said earlier this month during a trip to the Middle East. "It's a frequent occurrence."
Even if the U.S. military does not go after stockpiles it would probably try to target the specific units involved in carrying out the attacks if they can identify them, White said.
It's not clear how much intelligence the United States has on the Aug. 21 attack outside Damascus.
Secretary of State John Kerry said Monday the administration has additional information about the attack and "we will provide that information in the days ahead."
Some evidence suggests the attack was carried out by Syria's 4th Division, a unit intensely loyal to Assad that is protecting the capital, White said. Elements of that unit have lobbed artillery shells from surrounding hills into the city, he said.
But Pollack says the attack could have been carried out by a unit that was not firmly under Assad's control. That would complicate the administration's effort to send a message of deterrence to Assad's government.
"It's really hard to deter an entity that is not a unitary rational actor," Pollack said. "Maybe some generals don't respond to Assad."
Another question the administration will be examining is why or if the use of chemical weapons was authorized.
The attack occurred as rebel forces were engaged in fighting with government forces in eastern suburbs of Damascus.
Commanders generally turn to chemical weapons when they want to terrorize a population and intimidate civilians into not supporting rebels, analysts say.
"This is not really a military attack but part of psychological warfare," said Gregory Koblentz, a chemical weapons expert at the Council on Foreign Relations.