"I believe that killing an American citizen without a trial is an extraordinary concept and deserves serious debate."
Opposed to killing anyone without a trial?
Opposed to killing anyone without a trial?
Is it acceptable to bomb a tent of generals planning a campaign in the middle of a war?
Is the United States at war with Yemen? No.
Are the Yemenis being bombed civilians or military? Well, they're not the military of any particular state. We're in a murky territory here now, where the US gets to unilaterally declare war on individuals and deem them "not civilians" so it's ok to bomb them.
We are clearly not at war with Yemen. Yemen, the state, is cooperating with US efforts in their country.
The US gets to unilaterally go to war with individuals (that are part of a larger movement that relies on extreme violence against non-combatant civilians to achieve its goals, it is important to remember) because they've unilaterally gone to war with the US.