Republican lawmakers are currently lobbying to set a decorated military veteran free until he stands trial for war crimes allegedly committed while deployed in Iraq.

Special Operations Chief Edward Gallagher of the elite Navy SEAL Team 7 will face a military tribunal at a Navy base in San Diego next month.

A decorated veteran of combat missions in Iraq and Afghanistan, Gallagher stands accused of war crimes, including stabbing a teenage prisoner to death, picking off a young girl and an old man from a sniper's post, and firing machine guns and rockets into residential areas.

Members of Gallagher's platoon tampered with their leader's sniper rifle to make his shots less accurate and fired warning shots so civilians could attempt to flee before Gallagher fired on them, according to testimony heard at a preliminary hearing in November.

"They said they spent more time protecting civilians than they did fighting ISIS," Special Agent Joe Warpinski of the Naval Criminal Investigative Service told the court, using an alternate acronym for the Islamic State group (IS).

Despite those charges, Gallagher is considered a hero in the eyes of many Americans and the right-wing Fox News channel.

Around 40 Republican Congress members have penned a letter demanding Gallagher, who denies the charges against him, be set free until he stands trial. He has been held at the San Diego base since last September when he was arrested.

"They f---ed with the wrong family and ... we're going to fight this. We're going to fight this every step of the way," said Gallagher's younger brother Sean at a fundraiser on Friday, according to Fox News.

One lawmaker has even called on President Donald Trump to have the case dismissed.

The president has stated on Twitter that Gallagher will be "moved to less restrictive confinement" while he awaits his court date "in honor of his past service to our Country".

Gallagher was arrested after men under his command, horrified by his actions, complained to their superiors.

But many of the Navy SEALs were warned that speaking out could cost them their careers, according to a report by The New York Times.

Several members of SEAL Team 7’s Alpha Platoon had previously sought action against Gallagher but had been "brushed off" repeatedly.

Seven members of the platoon met with their troop commander in March last year, giving him the bloody details of Gallagher's alleged war crimes and demanding a formal investigation.

They were reportedly told to "stop talking about it", with troop commander Lieutenant Commander Robert Breisch allegedly warning that complaints could lead to sidetracked careers and even the revocation of the SEALs' elite status.

A few days after the meeting, Gallagher was awarded the Bronze Star for "valour under fire" in Iraq.

Gallagher was only arrested after the platoon members sought action outside of the SEALs.

He will face trial next month on charges including premeditated murder, attempted murder and obstruction of justice, allegedly committed in 2017 while deployed in Mosul, where US special forces were working alongside Iraqi troops to beat back IS fighters.

If convicted, Gallagher could be sentenced to life in prison.

Although Gallagher denies the charges, members of the SEAL team say their platoon leader boasted about the number of people he had killed.

Iraqi troops captured a wounded IS fighter who appeared to be around 15 years old in May 2017.

As a medic was treating his wounded, Gallagher came forward and stabbed the teenager in the neck and side several times, two members of the SEAL team said.

Gallagher then allegedly posed for a photo, holding up the teenager's head in one hand and the knife in another.

Also facing trial is Gallagher's commanding officer, Lieutenant Jacob Portier, who reportedly posed in the photo with the dead teenager.

Portier faces charges of failing to report Gallagher's alleged crimes and destroying evidence.

Navy prosecutor Chris Czaplak accused Gallagher of handing IS "propaganda… from heaven" by deciding to "act like the monster the terrorists accuse us of being".