Readers criticize President Trump over his bellicose statements on Iran. Also: Education for every child, citizen or not; the cost of war.

No one has claimed responsibility for the killings in the mostly Christian city of Jos, and the police have yet to arrest the gunmen.

© Reuters

The bombing campaign Mr. Trump is threatening in Iran could affect millions of Iranian civilians’ access to water, electricity and food.

© Tierney L. Cross/The New York Times

The bombing campaign Mr. Trump is threatening in Iran could affect millions of Iranian civilians’ access to water, electricity and food.

The United States helped create safeguards to limit the brutality of war, and now I fear President Trump is dismantling them.