At the beginning of paragraph 2, the phrase “The development of drone warfare has put these distinctions under stress” most…

Because of the precision and efficiency of drones, it has become harder than ever to argue against war.

Many people are worried that drones will make warfare too easy and therefore less morally objectionable.

Because of the precision and efficiency of drone warfare, it has become harder for governments to justify using conventional large-scale military violence, whether for self-defence, execution, or assassination.

Since drone warfare is a new phenomenon, it should be placed in a new category, one that is distinct from self-defence, execution, and assassination

It is relatively hard to say precisely whether or not the use of drone warfare can be classified as self-defence, execution, or assassination.