PORTLAND – Relatives of some long-serving Maine National Guard and Army Reserve members say they want to know why their loved ones are spending more time in war zones than some active-duty units.

Nancy Durst’s husband, Scott, a reservist in the 94th Military Police Company, is one of about 5,000 part-time soldiers told this month to cancel plans for their long-awaited homecoming because they’re staying in the Middle East for another three or four months.

“The reason they are not active duty is that they have other civilian jobs to go to,” Durst said. “They have done their time.”

Her husband has been deployed for 2 1/2 years of his five-year marriage, Durst said. He left his family and full-time job as a Maine Drug Enforcement agent in December 2002, 17 months after returning from Bosnia.

Brig. Gen. John W. “Bill” Libby, the head of Maine’s Army National Guard, spent part of last week at Fort Dix in New Jersey, welcoming home the 150 members of the 1136th Transportation Company, who returned to Maine on Monday.

Libby said he expects some members to leave the Guard after a long, frustrating deployment in Iraq.

“I think that unit’s going to be a challenge for us,” he said.

Many part-time troops said they would not re-enlist after the first Gulf War in 1991, then changed their minds and stayed. Given the short duration of that war, however, that doesn’t give Libby a lot of reassurance.

“We’re going to have some problems with retention in all of our units that we didn’t experience after Desert Storm, because this operation isn’t over,” Libby said. “The deployments continue, and there’s no end in sight.”

Besides the larger scale of this war, stabilizing Iraq demands troops with specialties that now exist almost entirely in the Guard and Reserve.

And a specialized Guard unit such as the 94th Military Police can be extended for more than a year while an active duty combat unit is sent home.

Many part-time soldiers and military families fully understand that the world and the military have changed, says Sam Jackson of Farmington. His son, Cpl. Samuel “Craig” Jackson, was deployed in January and is in Iraq with the 152nd Field Artillery Battalion from Waterville.

“This is the answer to not having a solid draft,” he said. “You’ve got to have something to back up the Army.”

Jackson says he understands that some other families are frustrated and losing patience. But he says the military needs to be able to react to threats in Iraq or anywhere.

Nancy Durst says her husband was proud to go to Iraq, even after having just served in Bosnia. But after two extensions, the second one only 10 hours before flying home, he and others are demoralized and planning to get out.

“He’s done,” she said.