Since U.S. Defense Secretary Chuck Hagel left for Southeast Asia last week, he has been wrestling with a dilemma at the heart of Washington's policy on Syria and Hagel's own guiding philosophy - when and how to go to war.
"I think the world has had enough war," Hagel told a forum in Kuala Lumpur, the capital of Malaysia.
He was responding to a question about the threat of conflict with China but broadened his answer to talk about war, generally.
"I think one of the things that we have learned over the years, regardless of the region of the world, is that wars can't resolve differences," he said on Sunday.
But Hagel hinted in Indonesia the next day that a limited intervention in Syria might be necessary, saying nations sometimes must go to war - including for humanitarian reasons.
He had told reporters toward the start of his trip that the United States couldn't wait indefinitely to respond to any confirmed use of chemical weapons. "If, in fact, this was a deliberate use and attack by the Syrian government on its own people using chemical weapons, there may be another attack coming," he said.
The Southeast Asia tour was meant to highlight President Barack Obama's bid to place greater U.S. attention to the Asia-Pacific region after more than a decade of frustrating war in places like Iraq and Afghanistan.
Hagel left on the tour last Thursday, just as more details were emerging of the extent of an apparent chemical weapons attack in which Syrian rebel groups say many hundreds of people were killed.
Before his modified Boeing 747 left U.S. airspace, Hagel, during a flight to a Hawaii, was dialed in to a White House meeting on Syria to give an update on military options as the Pentagon repositioned ships that might be called upon to act.
On every day of the tour, as global events gather pace, the former Republican senator has seemed to become more and more likely to oversee the first major U.S. military intervention since Libya and his first as defense secretary.
FIRST PERSON EXPERIENCE
Hagel, now 66, volunteered for the Vietnam War and fought alongside his own brother as an infantryman. He suffered shrapnel wounds and burns from mine blasts, earning two Purple Hearts - the decoration for troops wounded in battle.
When Obama announced Hagel's nomination for the job of defense secretary in January, he said Hagel was the kind of person American troops deserved, someone who could share their perspective. He quoted Hagel as saying: "My frame of reference...is geared towards the guy at the bottom who's doing the fighting and the dying."
Hagel earned Obama's respect during his Senate days in part for breaking ranks with fellow Republicans to oppose the Iraq war, where the U.S. military learned the hard way that its influence over sectarian tensions was limited at best.
"I think one of the reasons the president and he intellectually meshed so well...is that they share a view that the American military has unique capabilities to affect events throughout the world - but those capabilities should be used with great caution," said one senior Obama administration official, speaking on condition of anonymity.
If there was, before Obama, a truism that Democrats were reluctant to use U.S. military power and Republicans were eager to do so, Hagel "falls squarely in the middle."
"His first and second and third instinct is never to rush to military force," the official said.
Hagel's periodic warnings on Syria to Congress have frustrated former Republican allies of his, particularly Senator John McCain, the leading voice in Washington for deep U.S. military involvement in Syria's civil war.
At one hearing in April, Hagel cautioned senators including McCain that "you better be damn sure, as sure as you can be" before committing to action in Syria.
"Because once you're into it, there isn't any backing out, whether it's a no-fly zone, safe zone...whatever it is," Hagel told senators.
"Once you're in, you can't unwind it. You can't just say, 'Well, it's not going as well as I thought it would go so we're gonna get out.'"
Even as the United States hardened its posture in the past week over Syria's alleged use of chemical weapons, a "red line" that Obama set for greater U.S. involvement, Hagel has remained focused on the long-term implications of any U.S. military action there.
"What is the long-term objective here? What are our long-term interests? What are we trying to accomplish in the way of influence, in the way of outcomes?" he told reporters as he flew to Malaysia at the start of the tour, speaking about deliberations underway.
LIMITS OF ACTION
With U.S. international credibility on the line, Obama appears poised to act - possibly opting for limited measures such as cruise missile strikes to punish President Bashar al-Assad and seek to deter further chemical attacks.
But Obama is expected to stop well short of anything remotely resembling Iraq.
Obama, even as he said he had not yet made a decision on military action, argued on Wednesday that a "tailored, limited" strike, not a protracted engagement like Iraq, could be enough to send a strong message that the use of chemical weapons cannot be tolerated.
"If we are saying in a clear and decisive but very limited way, we send a shot across the bow saying, 'Stop doing this,' this can have a positive impact on our national security over the long term," he told "PBS Newshour" in a televised interview.
Still, whether any U.S. action can be limited to a short and sharp punitive strike, or whether it would drag the United States into a broader regional conflict, remains to be seen.
The White House has stressed that any action in Syria would not be geared toward regime change.
That could, at least in part, be because the United States doesn't think moderate rebel groups are ready to fill the void that would be left if Assad were to fall - a point suggested in a recent letter to Congress by General Martin Dempsey, chairman of the U.S. military's Joint Chiefs of Staff.
Dempsey - the top military advisor to Hagel and Obama - has been one of the most outspoken voices of caution on Syria, stressing the complexities of the conflict during a trip to the Middle East earlier this month, prior to the apparent chemical weapons attack.
Dempsey wrote in a letter to a lawmaker following that trip: "The use of U.S. military force can change the military balance, but it cannot resolve the underlying and historic ethnic, religious and tribal issues that are fueling this conflict."
Asked whether he shared Dempsey's views on Syria, Hagel said on Aug. 23: "Any time force is required or used, there are risks, there are consequences. And I think General Dempsey's analysis of this has been very accurate and very correct and very appropriate."
"There's no disagreement between General Dempsey and me on his analysis," Hagel said.
Still, what appears to have been the large-scale use of chemical weapons has fundamentally changed U.S. calculations on military intervention. It has certainly had an emotional impact.
Secretary of State John Kerry spoke on Monday of seeing images of entire families dead in their beds - without a drop of blood. Hagel, too, has been moved by the carnage.
"Another part of Chuck Hagel that is important here is that he really is horrified by scenes that we are seeing on the ground in Syria," the U.S. official said.
A second senior Obama administration official summed it up this way: Hagel, while recognizing the limits of military power, also understood that military action can sometimes be required "to deliver justice." That's particularly true when rules and norms of international law were violated, the official said.
Hagel told the BBC during a visit to Brunei that he had prepositioned assets and that the U.S. military was "ready to go" immediately, if ordered by Obama.
Just a day earlier, Hagel was asked how he could square his feelings that "the world has had enough war" with the looming possibility of U.S. military action in Syria.
Hagel's response spoke volumes.
"I didn't say, would never say, have never said, that no nation should ever go to war," Hagel said in Jakarta on Monday, declining to discuss the case of Syria explicitly.
"I wish the world was such that nations didn't go to war."