WASHINGTON — The Justice Department Thursday brought fresh charges against four former Blackwater Worldwide security contractors, resurrecting an internationally charged case over a deadly 2007 shooting on the streets of Baghdad.

A new grand jury charges the men in a shooting that inflamed anti-American sentiment in Iraq and heightened diplomatic sensitivities amid an ongoing war. The men were hired to guard U.S. diplomats.

The guards are accused of opening fire in busy Nisoor Square on Sept. 16, 2007. Seventeen Iraqi civilians died, including women and children. Prosecutors say the heavily armed Blackwater convoy used machine guns and grenades in an unprovoked attack. Defense lawyers argue their clients are innocent men who were ambushed by Iraqi insurgents.

The indictment revives a case that has lingered for years in Washington’s federal court.

The guards were charged with manslaughter and weapons violations in 2008, but a federal judge the following year dismissed the case, ruling the Justice Department withheld evidence from a grand jury and violated the guards’ constitutional rights. The dismissal outraged many Iraqis, who said it showed Americans consider themselves above the law. Vice President Joe Biden, speaking in Baghdad in 2010, expressed his “personal regret” for the shootings.

A federal appeals court reinstated the case in 2011, saying now-retired Judge Ricardo Urbina had wrongly interpreted the law.

Prosecutors again presented evidence before a grand jury, and U.S. District Judge Royce Lamberth gave the Justice Department until Monday to decide what to do with the case.

The defendants include Dustin Heard, a retired U.S. Marine from Knoxville, Tenn.; Evan Liberty, a retired U.S. Marine from Rochester, N.H.; Nick Slatten, a former U.S. Army sergeant from Sparta, Tenn., and Paul Slough, a U.S. Army veteran from Keller, Texas.

Slatten is charged with 14 counts of voluntary manslaughter and 16 counts of attempt to commit manslaughter; Liberty and Heard are charged with 13 counts of voluntary manslaughter and 16 counts of attempt to commit manslaughter; and Slough is charged with 13 counts of voluntary manslaughter and 18 counts of attempt to commit manslaughter. All four were also charged with one count of using and discharging a firearm during and in relation to a crime of violence.