In the tautological sense that murder means an illegal killing, sure. If a killing is legal, it is by definition not murder, and therefore any murder is by definition illegal.
Well, no. First, they're not simply accused of running drugs, but being active members of a designated foreign terrorist organization. Second, these military strikes can only occur outside US territory, not inside. So that's a pretty major limitation on this power.
Third, you're appealing to how you think it should work. I'm pointing out that it doesn't work that way. And my evidence is that presidents have been doing military strikes on such targets for decades now. This isn't new. This isn't unique to Trump. Obama did the same thing, the only difference is that he did it on the other side of the planet. But that's not legally relevant.