To others, the rules are the result of the coming home of troops from Iraq and Afghanistan.

“There’s a tendency during wartime to permit personal styles and variations in approach simply because more important things are at stake than how your hair looks or what tattoo is on your arm,” said Loren B. Thompson, a military expert at the Lexington Institute, a research organization. But now, he said, a smaller Army can “be more arbitrary about enforcing regimentation.”

Although the new rules on tattoos have come under fire, particularly since body art became popular among soldiers deployed in Iraq and Afghanistan, the regulations on black hairstyles have drawn more outrage and charges of racism. By Friday, more than 17,000 people had signed an online petition sent to the White House to get the hair regulations rescinded.

At the root of the concern about the Army regulations, many black women said, is a lack of understanding about black hair, coupled with a norm that uses the hair of white women as its baseline. While black hair comes in all textures, much of it is deeply curly, making it difficult, unless chemically straightened, to pull back into a bun or to hang loose off the face in a neat, uniform way.

“Our hair is kinky,” said BriGette McCoy, a former Army specialist, her voice getting angrier as she spoke. “It is genetic, it is hereditary, there is nothing we can do about it. And to have someone tell you that because your hair comes out of your scalp that way, you have to go and change it, when no one else is required to change that about themselves?”

In Ms. McCoy’s view, the new regulations are a further affront to what she views as longtime Army squeamishness about the hair of black women, who make up more than a third of active-duty women in the Army. Twice when she was working as an Army data communications specialist in Germany, she said, her superiors ordered her back to her barracks because her commanding officer deemed her hair “unkempt.”