The second big theory is a bit simpler: that the Assad regime was not a sustainable enterprise and it's clawing desperately on its way down. Most countries have some kind of self-sustaining political order, and it looked for a long time like Syria was held together by a cruel and repressive but basically stable dictatorship. But maybe it wasn't stable; maybe it was built on quicksand. Bashar Assad's father Hafez seized power in a coup in 1970 after two decades of extreme political instability. His government was a product of Cold War meddling and a kind of Arab political identity crisis that was sweeping the region. But he picked the losing sides of both: the Soviet Union was his patron and he followed a hard-line anti-Western nationalist ideology that's now mostly defunct. The Cold War is long-over and most of the region long ago made peace with Israel and the United States; the Assad regime's once-solid ideological and geopolitical identity is hopelessly outdated. But Bashar Assad, who took power in 2000 when his father died, never bothered to update it. So when things started going belly-up two years ago, he didn't have much to fall back on except for his ability to kill people.
4. I hear a lot about how Russia still loves Syria, though. And Iran too. What's their deal?
Yeah, Russia is Syria's most important ally. Moscow blocks the United Nations Security Council from passing anything that might hurt the Assad regime, which is why the U.S. has to go around the U.N. if it wants to do anything. Russia sends lots of weapons to Syria that make it easier for Assad to keep killing civilians and will make it much harder if the outside world ever wants to intervene.