PHILLIPS — Sgt. Richard K. Parker died after the vehicle in which he was riding in Iraq struck a sophisticated improvised explosive device, or IED, during a routine security detail, a Maine National Guard spokesman said.

Military authorities had not previously disclosed the cause of Parker’s death, which occurred Wednesday.

Capt. Shanon Cotta of the Maine National Guard said IEDs apparently have become more lethel, designed to have an explosive force that is more concentrated and therefore more potent than initial ones encountered by U.S. soldiers.