Washington (CNN) -- To those fighting for the right of Saudi women to drive, the issue seems to highlight the kind of discrimination against women that would be the perfect cause to elicit comment, and perhaps criticism, from U.S. Secretary of State Hillary Clinton.
But Friday, as some Saudi women, prevented by custom and religious edict from driving, turned the key in protest and hit the road, Clinton said nothing publicly.
"Where are you when we need you most?" wrote Saudi Women for Driving, the coalition of Saudi women's rights activists, bloggers and academics campaigning for the right to drive, in a letter sent to Clinton and her European Union counterpart, Catherine Ashton.
The letter, which the State Department said it had just received on Monday, continues: "In the context of the Arab Spring and U.S. commitments to support women's rights, is this not something the United States' top diplomat would want to publicly support?"
One reporter asked if Clinton is more concerned about not alienating Saudi Arabia when the United States needs the kingdom's help on Yemen and Bahrain than about defending women's rights. State Department spokesperson Victoria Nuland defended Clinton, saying she "has been engaged in quiet diplomacy."
For example, Nuland said, Clinton had a telephone conversation with Prince Saud that touched on other Mideast issues "and the subject of driving did come up."
"I don't think anybody can question the secretary's commitment to universal human rights for women," she said. "I think she is making a judgment on how best to support universal human rights for women. There are times when it makes sense to do so publicly, and there are times for quiet diplomacy."
The women's coalition says if Clinton speaks publicly in their favor, that could be a "game-changing moment."
A senior administration official, speaking on background because of the diplomatic sensitivity of the issue, said: "Let's wait and see where this goes. She's made her point at her level and let's see what conclusions are drawn in Saudi Arabia."
"The No. 1 issue in Saudi Arabia," the official said, "is that women are taking this issue into their own hands."