"We'll see. It really does remain to be seen whether the Iranians are going to honor their side of the deal. This is not a regime that typically does honor its word," Kirby said.
"We'd like to see this war in Yemen end and that this arrangement that they have might help lead us to that outcome," he said.
Asked about the unusual Chinese role in helping to bring together US ally Saudi Arabia and arch-foe Iran, Kirby said that Iran was brought to the table because of "the pressure that it's under" both abroad and from domestic discontent.
"We certainly continue to watch China as they try to gain influence and footholds elsewhere around the world in their own selfish interest," he said.
"But in the end, if this deal can be sustained, regardless of what the impetus was, or who sat down at the table ... in the end, we welcome that."
