When Staff Sgt. Tabitha Williams completed basic training for the U.S. Marine Corps at Parris Island, S.C., it was the proudest moment of her life.

The 13-week course -- the longest of any military branch -- ends with the Crucible, three days of sleep and food deprivation and obstacles that both men and women must overcome.

"I realized I could do anything I wanted to do," said Sgt. Williams, 27, a 5-foot-tall Marine recruiter in Ross who had the nickname "Little Tabby" as a teenager in Eastern Pennsylvania.

Today, the Marine Corps has more than 11,000 women, including more than 1,100 officers. About 200,000 women serve in active duty posts in the armed forces, 14 percent of the total.

Yet Sgt. Williams and her fellow female soldiers and Marines are far from being able to do "anything" in the military, a fact that irritates proponents of full gender equality. The Department of Defense prohibits women from serving with the infantry, special forces, armor, field artillery and on submarines.

But the nature of fighting in Iraq and Afghanistan has made some of those prohibitions obsolete, with insurgents targeting support units and putting all military personnel in harm's way, argues Lory Manning, a project director for the Women's Research & Education Institute in Arlington, Va.

Female medics, for example, sometimes accompany combat units into battle. And special forces teams bring female soldiers on missions to help them question Muslim women who are reluctant to cooperate with male soldiers.

Two women have won the Silver Star medal for valor in combat, the first to do so since World War II. Nearly 100 women have been killed in Iraq and Afghanistan.

"These women aren't asking for special privileges," said Ms. Manning, a Navy veteran. "We think women and men should be allowed to do any job they are physically qualified to do."

Elaine Donnelly, a former member of the "Commission on the Assignment of Women in the Armed Forces," convened by President George H.W. Bush, has sharply criticized both the Department of Defense and Congress for allowing these changes to take place without public debate.

"It's a cultural shift. It does concern me quite a bit," she said. "These women are patriotic. They're courageous. But we should not ask of our women and the military more than is realistic."

Ms. Donnelly, who heads the nonpartisan Center for Military Readiness, argues that ordering women to serve in combat is lowering standards and creating resentment among male soldiers. "There are differences between men and women where physical strength is an issue."

That's a point Ms. Manning, a Navy veteran, disputes.

"There are some pretty strapping women out there," she said.

When she joined the military in 1969, few positions were open to women. No woman could have command authority over men, nor could she serve on any Navy craft, except hospital ships and some transport ships.

By the time Ms. Manning retired 25 years later, more than 40,000 women had served in the first Persian Gulf War in 1990 and 1991. Thirteen were killed and two became prisoners.

In the first three years after the war, Congress allowed women onto combat aircraft and most Navy combat ships.

Defense Secretary Les Aspin issued a new rule for all women in the military, only keeping them from serving in units below the brigade level "whose primary mission is to engage in direct combat on the ground."

He also prohibited women from serving in support units that work side by side with combat units. The rule opened up 32,700 Army positions and 48,000 Marine Corps positions, according to the Women's Research & Education Institute.

Mr. Aspin's rule remains in effect today, at least officially. The Iraq war has shown limitations with his definition of direct combat occurring "well forward" on the battlefield.

During the first weeks of fighting, Iraqis attacked the 507th Ordnance Maintenance Company in Nasiriyah, capturing three women: Lori Ann Piestewa, Shoshana Johnson and Jessica Lynch.

Ms. Piestewa, 23, a Hopi Indian and a single mother with two young children, later died.

More than 25,400 women deployed during the early stages of Operation Iraqi Freedom, and many have seen fierce fighting.

Sgt. Leigh Ann Hester, a 23-year-old soldier with a National Guard unit from Richmond, Ky., won the Silver Star in 2005 after she and her fellow guardsmen fought off insurgents ambushing a supply convoy. Sgt. Hester's squad cut off the insurgents and attacked their trench. She killed three enemy fighters.

"These are things people said women just couldn't do," Ms. Manning said.

Neither branch of Congress has had a formal committee hearing on the role of women in the military in several decades, even though the Defense Department is required to let lawmakers know if changes are made to the Aspin rule. That has allowed the expansion of female roles on the battlefields, Ms. Donnelly said. "I don't think we have thought this through as a nation," she said. "Very few people are aware of it."

President Bush has said he opposes opening combat positions to women, an opinion echoed by Sen. John McCain, the GOP presidential nominee. But Sen. Barack Obama, the Democratic presidential nominee, would consider a change.

Sgt. Williams, the Ross recruiter, who has served in both Iraq and Afghanistan in logistical units, said she would take a combat position if it were open to her. Regardless, she plans to stay in the military and do her duty.

"They don't call me a female Marine," she said. "They call me a Marine."