Updated

As the Obama administration appears to move ever closer to a strike on Syria, the White House has confirmed that the Damascus suburb allegedly hit by chemical weapons was first under assault by the Syrian military.

That information can help piece together answers to several key questions that form the basis of the highly anticipated, declassified intelligence assessment being prepared by the Office of the Director of National Intelligence (ODNI): Who was behind the attack? Who controlled the delivery system? And who would have been in the chain of command for decision making?

When using a chemical agent, one common practice involves test firing, mostly commonly with missiles, which have a greater accuracy than rockets.

Tracking the movement of smoke from the missiles, either toward or away from the target, can “bracket” the target and determine how chemical agents are launched in a second round (of launches.) After this preliminary phase, the chemical agent is loaded and fired at the target.

Sources familiar with the Damascus attack tell Fox News that the rocket attack included both conventional and chemical weapons warheads. The timing, coming in the early morning hours, is seen as a deliberate effort to maximize the impact of the chemical agents, which are typically a watery consistency that can evaporate with sufficient sunlight.

On Tuesday, administration officials at both the White House and State Department told reporters that there is no credible reporting that Syrian opposition groups have the ability to deliver a chemical weapon -- in other words, they don't have the rockets nor do they control Syria's chemical weapons stockpiles.

"It's not circumstantial evidence that the regime maintains custody of these kinds of weapons.  We have a broad array of information that points to that, that they've -- that they are the only ones that have the capability to use these kinds of rockets and delivery systems, that the opposition does not have those capabilities," State Department Spokeswoman Marie Harf said.

"It is abundantly obvious to those who have covered this conflict,” White House Spokesman Jay Carney explained. “The Syrian regime was engaged in an effort to clear these particular regions of opposition forces with violent force prior to the use of chemical weapons."

Harf and Carney's statements appear to check two important boxes that point to the Syrian regime's culpability.

The official intelligence assessment by ODNI, which was still ongoing Tuesday night, is also considering whether a single nerve agent, such as Sarin gas, was used or whether it was a so-called "cocktail" of agents.