SCHOFIELD BARRACKS — In an exercise involving 4,000 computers and more than 7,000 service members and civilians in Hawai'i and on the Mainland, the 25th Infantry Division yesterday was again planning for war.

The simulation included six Army brigades, along with Air Force and Marine personnel.

In one scenario, a car bomb rocked a U.S. base in northern Iraq, injuring two. In another, commanders had to deal with an outbreak of meningitis, resulting in two fatalities.

Crisis action teams stand at the ready to provide information to Maj. Gen. Benjamin R. Mixon, who in coming months will be in charge of U.S. forces in a quarter of Iraq and a region roughly the size of Pennsylvania.

The "Mission Rehearsal Exercise," which started yesterday — and will be under way 24 hours a day, seven days a week through June 23 — is the last major training event before the deployment of 7,000 Schofield Barracks soldiers in July and August.

A deployment ceremony is scheduled for July 7.

Another battalion of about 1,000 Kane'ohe Bay Marines, the 2nd Battalion, 3rd Marine Regiment, is preparing for Iraq duty as well. The 3rd Battalion, 3rd Marines are now in northwestern Iraq.

Mixon said a priority will be working with the Iraqi Army and border and infrastructure security forces, and Iraqi police.

"The challenge is building the economy and the protection of the infrastructure from insurgents," Mixon said. "The insurgents know that if oil production picks up, electricity capacity picks up — and it will as the Iraqi security forces stand up more and more — that they then have lost (their) leverage."

Spc. Justin Folsom, 22, yesterday had more immediate concerns, such as dealing with a roadside bomb that just hit one of four Humvees in his convoy during simulator training.

"Enemy! Enemy in front of us!" the Humvee driver from Naples, Fla., warned as four insurgents ran toward the vehicles. "Gunner, take out the enemy. Let's go!"

Convoy training and firing range practice are still being conducted, and there remain paperwork issues like powers of attorney and wills. The upcoming deployment is the largest for Schofield Barracks yet to the Iraq war.

Through 2004, 5,200 Schofield soldiers served in Iraq. Thirteen were killed.

About 100 helicopters will be sent to Iraq. The division has in its inventory 45 UH-60 Black Hawks, 10 CH-47 twin-rotor Chinooks and 55 OH-58-D Kiowa Warrior scout and reconnaissance helicopters.

Mixon will take over Multinational Division North from Maj. Gen. Thomas Turner II and the 101st Airborne Division (Air Assault), which assumed responsibility for the region on Nov. 1.

The region includes a population of 10.2 million that extends north of Baghdad to the border with Iran in the east, Turkey in the north, and Syria in the west.

Saddam Hussein's hometown of Tikrit, as well as Mosul, Tal Afar, Baiji, Baqubah — near where Abu Musab al-Zarqawi was killed — and the oil-producing city of Kirkuk are part of that area of responsibility. Kirkuk was the headquarters for Schofield's 2nd Brigade when it deployed in 2004.

In November, the headquarters for Multinational Division North moved out of an 18-palace compound in Tikrit on the Tigris River and to nearby Forward Operating Base Speicher.

The Mission Rehearsal Exercise is being conducted with elements of three deploying Schofield brigades — the 3rd Brigade, 45th Sustainment Brigade, and 25th Aviation Brigade — as well as three Mainland brigades expected to be under Mixon's control.

Those units are the 3rd Brigade of the 82nd Airborne Division, the 3rd Brigade of the 1st Cavalry Division, and the 3rd Brigade of the 2nd Infantry Division at Fort Lewis. Wash., which earlier this month started sending nearly 4,000 of its soldiers to Iraq.

A 70-foot by 50-foot Tactical Operations Center with 54 computers and five projection screens is the nerve center at Schofield for the exercise classified "secret."

That's contained within the $33 million, 90,000-square-foot Battle Command Training Center. The site opened at Schofield in November and will serve as a Pacific-area training center.

The Joint Warfighting Center in Suffolk, Va. and planners on the second floor of the Schofield facility can alter scenarios as they go. The Air Force at Davis-Monthan Air Force Base in Arizona has a part in the virtual war with simulated F-16 and A-10 aircraft providing close-air support. Marine support comes from Camp LeJeune in North Carolina.

In Iraq, Mixon will have many issues to keep him busy.

"He's looking at not only the kinetic operations you've heard in the news, (but) much of the emphasis now is to allow the Iraqis to provide their own security," said Lt. Col. Michael Staver, the simulation officer.

Turner, in a press briefing from Iraq last month, said U.S. forces in northern Iraq are partnered with 15 Iraqi Army brigades, and of those, three are "in the lead" in their areas of operation.

Insurgents have targeted oil pipelines in the north, and Mixon said "we've got Iraqi infrastructure security battalions that we are working to train and equip, along with Iraqi Army forces."

"Their numbers will increase, and they will be given sectors of the pipeline and also the electrical lines that run from the north into Baghdad to protect," Mixon said. "The more of those that we stand up over the period of a year, the more we'll be able to secure those particular lines, and that will take the advantage away from the insurgents."

By the end of the 25th Division's year in northern Iraq, Mixon said he expects Iraqi security forces to be in control of more than half that area, with U.S. forces providing support.

Folsom, who was behind the wheel of a Humvee simulator with a commander and turret gunner — complete with rotating turret — spent a year in Afghanistan with the 25th Division.

"I think it will be very different terrain. It seems like there are more buildings out there (in Iraq)," Folsom said.

The virtual reality training, with a variety of attack scenarios, is good preparation, he said.

"It gets you where your head needs to be, so you know what to do," he said.

Reach William Cole at wcole@honoluluadvertiser.com.