The Obama administration is considering a major expansion of the scope of U.S. airstrikes in Iraq to target the logistics hubs and supply lines of militant Islamic State forces, in operations intended to help Iraq’s new government retake lost territory.

The new phase would represent a departure from the past month, when American military forces confined their operations to categories such as protecting U.S. personnel in the northern city of Erbil, humanitarian relief operations and defending key Iraqi infrastructure from the militants’ advance.

A new category of strikes is designed to have a wider effect. Some U.S. officials said airstrikes over the weekend at Haditha dam were a first example of the potential of an expanded air campaign, one closely coordinated with Iraqi forces. […]