WASHINGTON - The tanks, Bradley fighting vehicles, and Apache and Kiowa helicopters have been shipped out. Now, the 12,000 men and women of the 4th Infantry Division at Fort Hood in Texas, the Army's most lethal heavy combat division, are saying goodbye and preparing their families for their deployment to the Persian Gulf region.

"Just like everyone else, I'm excited and a little nervous," says Capt. Shoshannah Jenni of Ocean City, N.J.

Jenni, a West Point graduate, is among the growing pool of women who have chosen military careers. But at 25, the Kiowa Warrior pilot is also part of a newer and more exclusive club: women in positions, many of them combat-related, that until recently had been restricted to men.

Changes in law and policy since the Persian Gulf war have opened up thousands more positions to women. In Iraq, women would serve in greater numbers, closer to front-line combat and more integrated into core operations than in any previous U.S. military conflict.

Unlike the gulf war of 1991, women would probably be in the cockpits of fighter jets, bombers and Apache attack helicopters during an opening air assault. And women such as Jenni would probably be in armed reconnaissance aircraft that scout enemy troops and targets.

Women would also be part of ground combat-related operations - as combat engineers building bridges for soldiers to cross the Euphrates River to enter Baghdad or as chemical officers leading the way through contaminated areas. They would also be on aircraft carriers and command warships.

"If the force is committed, the women will be there," says Evelyn "Pat" Foote, a retired Army brigadier general who formed the Alliance for National Defense to advocate for women in the military. "In fact, we could not do it - we could not perform the mission that's being anticipated and that we're staging for - without the women in the active and reserve corps."

Women make up about 15 percent of the active-duty force - up from 11 percent during the gulf war - reflecting a steady increase since the 1970s. They make up a larger portion of the reserves - nearly 25 percent of the Army Reserve, for instance.

The Pentagon still bars women from ground units that are intended to fight the enemy directly. But the changing nature of warfare, with higher-tech and longer-range weaponry, has blurred the definitions of "combat" and "front lines."

During the American invasion of Panama in 1989, female soldiers and support units that included women exchanged fire with enemy forces. And in the gulf war, Iraqi Scud missiles attacked bases in Saudi Arabia and Israel, putting all military personnel at risk.

"There was no less danger being on a supply ship than a combat ship," says retired Navy Capt. Lory Manning, director of the Women in the Military project for the Women's Research and Education Institute. "There's no more 'battlefield.'"

Removing bans

The gulf war involved the largest deployment of U.S. women to date - about 41,000, or 7 percent of total forces. Out of about 300 Americans killed, 13 were women. Two were taken prisoner and released. After the war - and in large part because women performed ably, according to a Government Accounting Office report - the last remaining legislative barriers were lifted.

In 1991, Congress repealed the ban on women flying combat aircraft in the Air Force and Navy, though the Pentagon waited two more years to implement the change.

In 1993, Congress lifted the ban on assigning women to combat ships. The next year, Defense Secretary Les Aspin scrapped the rule that barred women from assignments with a high risk of facing hostile fire or capture. In its place, the Pentagon adopted a rule barring women only from units "whose primary mission" is ground combat.

That meant generally that women could perform in any position except in front-line infantry, armor or artillery units or Special Operations forces. Each service, though, could interpret and apply the rule as it saw fit.

In the Army, women are excluded from 9 percent of all occupations or nearly 30 percent of active-duty positions. In the Marine Corps, 7 percent of all occupations are closed to women, accounting for 38 percent of all active-duty positions.

By contrast, 99 percent of all occupations and positions in the Air Force are open to women. In the Navy, women are excluded only from SEAL teams and, because of the expense of providing separate female quarters, from service on submarines and some small combat ships.

"We are everywhere and all over the fleet," says Lt. Cmdr. Pauline Storum, a Navy spokeswoman.