Is there a logical reason the US hasn't assassinated Bashar al-Assad? It's a pretty unsavory idea, but "given how far we appear willing to go in prioritizing American security interests, it doesn't seem very radical," argues Peter Beinart of the Daily Beast. You might argue that the US shouldn't be in the business of targeted assassinations. "But of course, the United States is in the business of targeted assassinations." Just ask Osama bin Laden or Abu Yaha al-Libi.
But those guys were part of al-Qaeda, you'll counter, and hence at war with America, whereas Assad is killing his own people. But the US has killed to stop regimes from killing their own people before; just look at Kosovo, Bosnia, and Libya. It's not that Beinart thinks we should assassinate Assad; he's just pointing out the direction US security policy has taken. "It’s hard to discern any principle that distinguishes killing Assad from the targeted assassinations and humanitarian wars that command significant American political support."