Sen. John McCain was back in Arizona on Thursday, explaining his push for U.S. action against Syria to crowds of skeptical constituents.

“I promise you it is ample evidence, and you will see a lot more, including intercepts that … will be made public about how Bashar al-Assad’s people ordered these chemical weapons to be used,” the Republican senator said in response to a question from a skeptical individual at a town hall meeting in Tucson.

Existence of those communications have been reported by numerous media outlets, including in a lengthy report by Foreign Policy. The Associated Press reported Wednesday that U.S. intelligence didn’t get the intercepts processed before the chemical weapons attack took place in August.

The individual who asked the question leading to McCain’s comments about the intercepted communications was — like McCain — a pilot during the Vietnam War (though the constituent noted that he did not spend time in a Vietnamese prison).

The individual heard applause from the crowd when he suggested the U.S. should wait until after United Nations weapons inspectors complete their report.

“Who stood to gain by this chemical weapons attack? It wasn’t Syria; they were winning the war. It was the rebels or the United States that supported them,” the constituent said. “So, I think we should wait for the United Nations to come back with their report on that.”

In addition to noting the intercepts, McCain responded by explaining the rationale for which Assad, Syria’s president, stood to benefit from a tactical standpoint in the civil war.

“The Free Syrian Army controls the part of Damascus that is vital to his communications and his ability to move his people back and forth, and he was not able to dislodge them from that particular place using a lot of weapons and tanks and armor, and so he decided that he would wipe them out,” McCain said.

The same person referred to the spraying of napalm in Vietnam as a defoliant, in what was an effort to note that the United States has used chemical weapons in the past.

“Napalm is a terrible weapon, and a relatively effective one as you know, and wars are terrible,” McCain said, before adding, “But … if you dropped napalm, you had an enemy, and war is hell, and if you killed that enemy, you probably prevented that enemy from killing one of our … people. That’s the object of war.”

“That in my view is very different from sending a scud missile loaded with gas that kills everybody in the vicinity that are innocent men, women and children. That’s what I think is a bit of a difference here,” McCain added.

McCain held two town hall meetings Thursday — the first in Phoenix and the second in Tucson. In each venue, he encountered resistance to his advocacy for a limited military strike in response to the use of chemical weapons in Syria.

In Phoenix, McCain faced an emotional plea from an attendee who was from Syria, a woman whom KTAR radio identified as Jumana Hadeed. She said she considered herself a longtime McCain supporter.

“I have a cousin who is 18 years old, just was killed 10 days ago by the so-called rebels and al-Qaida, and they’re not Syrian. They’re coming to Syria from all over the world to fight this. We cannot afford to do that. We cannot afford to turn Syria into another Iraq or Afghanistan. I beg you,” Hadeed said.

“All I can tell you is that I, too, have been to Syria, I, too, know the people who are fighting there. I met them, I know them and I know who they are,” McCain responded. “And I know Syria well enough to know that it is a moderate nation. It is not a nation that will embrace these foreign fighters, but to say that Bashar Assad is anything but a merciless butcher, then we have a strong disagreement.”

NBC News has video of the full exchange between McCain and Hadeed.