As the nation’s military and civilian leaders debate the size of a drawdown expected to start in Afghanistan in July, record numbers of Hawaii-based troops are projected to serve in the country for years to come.

State adjutant Maj. Gen. Darryll D.M. Wong announced yesterday that the Hawaii Army National Guard’s 29th Infantry Brigade Combat Team was told to prepare for a possible deployment to Afghanistan in 2013.

More than 2,000 Hawaii soldiers and 1,600 from Guam and Arizona would be part of the deployment, but not the Army Reserve’s 100th Battalion, 442nd Infantry Regiment, which had fallen under the 29th Brigade for past combat duty in Iraq and Kuwait, officials said.

The notification also appears to have moved up the Hawaii National Guard’s next possible deployment. Maj. Gen. Robert G.F. Lee, who recently stepped down as the state’s adjutant general, said in January that 2014 was the earliest the Hawaii troops needed to be ready to deploy. Officials could not explain yesterday why the “ready year” apparently was moved up.

“At this time, the Army Reserve’s 100th Battalion, 442nd Infantry Regiment has not been sourced for the 29th IBCT’s potential 2013 deployment,” Lt. Col. Kimo Dunn, the unit’s commander, said in an email.

Meanwhile, about 1,000 Kaneohe Bay Marines with the 2nd Battalion, 3rd Marine Regiment have been serving since November in Nawa and Marjah in southern Helmand province.

The battalion lost its first Marine of the deployment, Lance Cpl. Harry Lew, 21, of Santa Clara, Calif., on Sunday when he died “while supporting combat operations,” the Pentagon said.

Nawa often is cited as the poster child of stability that the presence of U.S. forces has brought to some former Taliban strongholds in the south.

Marine officials said another Hawaii unit, the 1st Battalion, 3rd Marine Regiment, had its deployment moved up by about three weeks, and those 1,000 Marines will start deploying this week to Garmsir district 20 miles south of Nawa on the main route from Pakistan into Helmand.

The early deployment will temporarily double the number of Hawaii Marines that are usually in Afghanistan; until now the base’s three infantry battalions have rotated one after another to the country.

“Really, what we’re looking at, it’s an IED (improvised explosive device) environment,” Executive Officer Maj. John W. Black said of Garmsir. There are few firefights, but on average, 21 IEDs are found daily, he said.

Although some areas of Helmand have come under Marine control, others have taken a huge toll on American forces. Sangin, in northeastern Helmand, was called one of the most dangerous places in Afghanistan by Defense Secretary Robert Gates.

Since October the 3rd Battalion, 5th Marine Regiment out of Camp Pendleton had suffered 29 Marines killed and 175 wounded in Sangin — the heaviest losses for a battalion in the 10-year war, Gates said during a visit to Afghanistan on March 8.

The 3rd “Bronco” Brigade of 3,500 soldiers from Schofield Barracks, led by McKinley High graduate Col. Richard C. Kim, is taking over in Kunar, Nuristan and Nangarhar provinces on the eastern border with Pakistan.

Additionally, about 2,600 Hawaii soldiers with the 25th Combat Aviation Brigade are expected to begin flying missions in southern Afghanistan in January.