Those with limited power must normally use weapons to kill. Those with unassailable power can kill by simply making a rule.
If a pet owner tethers a dog to a tree and then neglects to feed it, he or she is rightly accused of killing the dog should it perish. In the same way those who unfairly distribute the goods of the world, and then allow human beings to perish through political neglect are guilty of those deaths. The weak have visible weapons. The strong can hide their violence behind laws, treaties, prisons, customs and anything that codifies discrepancies of wealth and power.
Just as a person is guilty when using overt weapons of violence, so are those guilty who use covert weapons like laws that do not allow others to meet their basic needs. Such powerful people are guilty of murder by leash.