US Army introduces new blast grenade designed for indoor combat

The United States Army has introduced the M111, its first new lethal hand grenade since the Vietnam War, aimed at improving effectiveness in confined combat environments while reducing unintended damage.

The M111 is designed to rely on blast overpressure rather than fragmentation to neutralize targets. According to an Army fact sheet, "When the high-pressure wave encounters someone, it violently compresses and decompresses tissue." The grenade vaporizes its plastic casing on detonation and generates a powerful shock wave rather than dispersing shrapnel, says CNN.

The weapon is intended primarily for urban warfare, including clearing enclosed spaces such as rooms or buildings. Col. Vince Morris, project manager at Picatinny Arsenal, said: "A grenade utilizing BOP [blast overpressure] can clear a room of enemy combatants quickly leaving nowhere to hide while ensuring the safety of friendly forces."

Military officials said the grenade was developed following operational lessons from Iraq. "One of the key lessons learned from the door-to-door urban fighting in Iraq was the M67 grenade wasn't always the right tool for the job. The risk of fratricide on the other side of the wall was too high," Morris said.

Unlike fragmentation weapons, the M111's blast effect can reach targets behind barriers such as interior walls, furniture or appliances. An Army fact sheet said: "The eardrums, lungs, eyes and gastrointestinal tract are most at risk of rupture and serious damage from smaller blasts." It added: "Larger blast waves can damage the brain or even amputate limbs."

The Army said the M111 will complement rather than replace the M67. Troops are expected to continue using the M67 in open terrain, where fragmentation remains more effective. In a statement, the Army said soldiers will use the M67 in such conditions "to maximize lethal fragment effects."

The introduction of the M111 fills a capability gap left after the withdrawal of the MK3A2 grenade in the 1970s, which was removed from service due to the presence of asbestos.

Similar blast-based technologies are also in use elsewhere in the US military. The United States Marine Corps has acquired the M21 blast overpressure grenade, while thermobaric munitions—designed to generate shock waves and pressure effects through fuel ignition—have also been deployed in certain operations.