Governments in the Mideast and Africa, in desperate efforts to gain battlefield ground, are using barrel bombs against their enemies, launching the cheap, quickly manufactured weapons as a crude counter to roadside blasts and suicide explosions that insurgents have deployed for years.

New evidence of their use in Iraq, after being dropped on civilians in Syria and Sudan, has raised concerns that governments in unstable nations will embrace them.

Described as “flying IEDs,” or improvised explosive devices, barrel bombs have the power to wipe out a row of buildings in a single blast. They can kill large numbers of people, including those not targeted. […]