WASHINGTON - The role Defense Secretary Chuck Hagel and Joint Chiefs of Staff chairman Gen. Martin Dempsey played at the hearing today before the Senate Foreign Relations Committee was largely to support Secretary of State John Kerry's case for a limited U.S. military action against Syria.

Beyond Hagel's opening remarks both had some brief moments where they made clear points as to why they support such a move.

Both Hagel and Dempsey were asked why they seemed to have changed their minds about previous stands about the costs of a Syrian intervention.

Hagel said "the dynamics have changed" and he noted the administration is seeking authorization for "a very specific and focused military action."

Dempsey made the point that the task of the limited U.S. military action against Syria is "to deter and degrade, and to be limited in scope and duration."

Dempsey explained that in his previous statements the military options he presented were linked to national security interests and whether they could be effective. He said that in Syria's use of chemical weapons against its own population he finds "clear linkage to our national security interest."

The chairman of the Joint Chiefs of Staff acknowledged that Syria has been moving its equipment around during the delay to seek authorization from Congress. But he said the Syrians were reacting to what he called the "significant leak" of the military plans for a limited action against Syria, namely the use of Tomahawk cruise missiles to strike at command and control centers for chemical weapons units, as well as delivery systems for chemical weapons.

"There is evidence, of course, that the regime is reacting not only to the delay, but also they were reacting before that to the - to the very unfortunate leak of military planning," Dempsey said.

But while the delay may be helping the Syrians prepare, Dempsey also said: "Time works both ways."

"We have some pretty significant intelligence capabilities, and we continue to refine our targets," he said.

He even said that members of the senior national security team have discussed the idea that some targets are "becoming more accessible than they were before."

Dempsey did not provide details on the U.S. military's targeting other than to say they are being selected with the ideal of degrading Syria's chemical weapons capability. He also hinted that there might be two waves of targets.

"It won't surprise you to know that we will have not only an initial target set but subsequent target sets should they become necessary," he said.

Both Hagel and Dempsey said the White House has asked that there be low "collateral damage" from the strikes.

When asked if a limited action might escalate the Syrian conflict, Dempsey said that there's always that risk from the Assad regime "but they have significantly limited capabilities to do so." He alluded to intelligence informing that analysis, but said he could only talk about it in classified session.

Ultimately Hagel stressed that the Obama administration believes that the "end game" for Syria must be a diplomatic settlement, namely to keep Syria from breaking apart should the Assad regime collapse.

"We do not want to see the country of Syria disintegrate, result in ungoverned space, which I think the consequences would be devastating for our partners, for our allies, the entire Middle East," he said. "Then we would all have to respond in some way."