WASHINGTON (AP) -- The Obama administration is still defining the central objectives of a potential military strike on Syria and considering possible Syrian government reprisals, even as U.S. intelligence agencies prepare additional evidence to show the Bashar Assad government's responsibility for last week's alleged chemical weapons attack, two senior administration officials said Wednesday.
One of the officials also said the administration is considering more than a single set of military strikes. "The options are not limited just to one day" of strikes, the official said, adding that no additional U.S. defensive weapons have been deployed in the region in anticipation of Syria reprisals. The U.S. already has Patriot anti-missile batteries in Jordan and Turkey.
The other official said the administration has determined it can contain any potential Syrian military response in the event that President Barack Obama orders a U.S. attack, which likely would be led by low-flying cruise missiles fired from any of four U.S. Navy destroyers off Syria's coast. But the manner and timing of Syria's response are among the so-called "next day" questions that the administration is still thinking through as it prepares a possible military action, the officials said.
Both officials were granted anonymity in order to discuss internal deliberations on the highly sensitive and complex questions that surround crafting a response to the Aug. 21 attack in which hundreds of Syrian civilians were killed.
The administration in recent days has made clear it believes it must take punitive action against Syria for its alleged use of chemical weapons, which are banned by international convention, but the senior administration officials' comments Wednesday made clear that questions about the central purpose of using military force in this circumstance are still being worked out.
The officials said diplomatic and legal issues also are still being discussed internally.
In broad terms, the U.S. and international objective of striking Syria would be to damage the Syrian government's military and weapons enough to make it difficult to conduct more chemical weapons attacks, and to make Assad think twice about using chemical weapons again.
One administration official said Wednesday the administration also is concerned that if Assad is not punished, dictatorial leaders of other nations in possession of chemical weapons, like North Korea, might see the failure to act as a sign that they, too, could get away with using the weapons.
Administration officials have said Assad's actions posed a direct threat to U.S. national security, providing Obama with a potential legal justification for launching a strike without authorization from the United Nations or Congress. However, officials did not detail how the U.S. was directly threatened by an attack contained within Syria's borders. Nor did they present concrete proof that Assad was responsible.
"Allowing the use of chemical weapons on a significant scale to take place without a response would present a significant challenge to, threat to the United States' national security," White House spokesman Jay Carney said Tuesday.
Assad has denied using chemical weapons, calling the allegations "preposterous."
The U.S. and its international partners were unlikely to undertake military action before Thursday. That's when British Prime Minister David Cameron will convene an emergency meeting of Parliament, where lawmakers are expected to vote on a motion clearing the way for a British response to the alleged chemical weapons attack.
The prime minister's office said Wednesday that it will put forward a resolution to the U.N. Security Council condemning the Syrian government for the alleged chemical attack.
Obama and Cameron spoke Tuesday, their second known conversation since the weekend. A Cameron spokesman said the two leaders agreed that a chemical attack had taken place, and that the Assad regime was responsible.
Also Tuesday, Vice President Joe Biden became the highest-ranking U.S. official to charge that Assad's government fired chemical weapons last week near Damascus.
"There's no doubt who is responsible for this heinous use of chemical weapons in Syria: the Syrian regime," Biden said.
Ahead of any strike, the U.S. also planned to release additional intelligence it said would directly link Assad to the Aug. 21 attack in the Damascus suburbs. Syrian activists said hundreds of people were killed in the attack. A U.S. official said the intelligence report was expected to include "signals intelligence" - information gathered from intercepted communications.
Even before releasing that information, U.S. officials said they had very little doubt that Assad was culpable in the attack, based on witness reports, information on the number of victims and the symptoms of those killed or injured, and intelligence showing the Syrian government has not lost control of its chemical weapons stockpiles.
Other administration officials echoed Biden's comments, which marked a subtle shift in the administration's rhetoric on who bears responsibility for the attack. Earlier in the week officials would say only that there was "very little doubt" Assad was responsible.