All I can say is that they don't pay State Department spokesperson John Kirby enough.
[warning: awkward moment]

How does one defend the indefensible? I'm not qualified for this job.

Mr Lee, the AP’s diplomatic correspondent, continued to hold Mr Kirby’s feet to the fire on the Yemeni issue, pressing him for an answer on how “an increasing number of Yemeni civilians are at risk and being killed by weapons that the United States has furnished to the Saudis and their coalition partners.”
“You don’t find any kind of issue with this? Because a lot of people do, including on [Capitol] Hill,” he added.
Mr Kirby said that the situation was very different in Syria and Yemen, pointing out that Iranian-supplied Houthi rockets have killed Saudi citizens in recent months.
“The Saudi-led coalition were invited in by the Yemeni government - now I know what you’re going to say, the Russians were invited by [Syrian President] Assad… but [the Saudis] are under real threat on their side of the border in that war,” he said.

Oh, well that changes...uh, nothing at all.

Earlier this week, an investigation by Reuters revealed that State Department officials and lawyers in Barack Obama’s administration did not come to a conclusion on whether the US could be legally defined as a ‘co-belligerent’ in Yemen’s war before selling Saudi Arabia armaments worth $1.3 billion last year. 

For those of you unfamiliar with the very careful parsings of the truth by the State Department, consider this one from their greatest hits collection from a couple months ago.

In early July, an Amnesty International report named them as one of several US-backed group involved in torture and summary executions. Just two weeks later, the group’s social media accounts showed fighters beheading a young Palestinian boy described as “an Assad soldier.” Now, Russia is suggesting this same group was responsible for a chemical weapons attack this week in Aleppo.
That’s a lot of bad publicity for a matter of a few weeks, and is starting to come up in State Department briefings, though spokesman Mark Toner downplayed the incidents, or the possibility that the US would stop arming Nour al-Din al-Zinki just because they beheaded a child and used chemical weapons.

I would like to present to you the exact wording from the press conference so no one can say this is taken out of context.

QUESTION: So what does a rebel group in Syria have to do to not receive U.S. funds any longer? What is the line that they must cross? What kind of controversial incident must take place for a group to stop receiving U.S. funds?

MR TONER: Well, first of all, there’s a lot of vetting of the Syrian moderate opposition that has already taken place, and it’s not just by the U.S., but it’s by all the members of the ISSG and, frankly, the UN. And it was established that al-Nusrah as well as Daesh or ISIL were considered to be by all members and by the UN to be terrorist organizations. I think, again, these are not easy processes, and one incident here and there would not necessarily make you a terrorist group.

Wow! Just wow.