Getting a handle on Yemen is a bit of a struggle. It's in the news this week as Shia northerners, the Houthis, took over the capital of Saana, forcing the resignation of president Hadi.
Hadi is a southerner, a Sunni military guy with extensive overseas training, the kind of guy Westerners and Saudis can do business with. Hadi took over only in 2012, when the Arab Spring forced the former president to resign.
Yemen has been a mess since getting loose from British oversight. The country was split into northern and southern countries for many years, with the southern side being allied with the Soviets during the Cold War. Both the northern and southern sides went through civil wars inside themselves, and have only been reunited since the end of the Cold War. The resulting unified government wasn't all that unified, without a coherent consensus of governance.
As of late, we have a three-ring circus, with the southern side split between the government faction and the now-infamous Al Qaeda in the Arabian Peninsula. AQAP holds large chunks of territory on the southern coast, acting something more like ISIS than your stock terror group. The Charlie Hebdo shooters were AQAP fans, with one of them getting training there.
Iran backs the Houthis, although the Yemeni brand of Shia is a different faction than the Iranian version. The Houthis can be heard mouthing Iranian-style death-to-America-and-Israel chants (according to a public radio show on Yemen I listened to yesterday), but they also don't like AQAP, since they have quite a bit of anti-Sunni rhetoric in their "Fiver" theology. That makes them possible partners in the continuing droning of AQAP targets, but on an enemy-of-my-enemy basis at best.
The US doesn't have much of a coherent interest in Yemen other than tamping down AQAP and making sure it doesn't devolve into a pirate haven on the east side of entrance to the the Red Sea to match the Somali side on the west. There isn't much of a nation to build there, even if we were in the market for nation-building there.
The retired diplomat on the To The Point public radio panel pointed out that the drone strikes tend to radicalize the clans of those hit, creating more jihadis then they kill. However, not all jihadis are created equal. Spawning 10 low-grade warriors might be worth it if you kill off a general.
"Boots on the ground" doesn't seem to be a great option, since we wouldn't have a clear objective that the current whack-a-jihadi drone game (with some occasional special ops) can't handle. I don't see the Obama team wanting to play the new colonial power and occupy the place, nor do I see it helping much.
This is one with no real good options other than trying to not let things metastasize into ISIS South.