In last week’s New York Times op-ed, “When Women Rule,” Nicholas Kristof referenced a telling case study of Indian women who (by law) form one-third of village council positions. The study found that women ran the villages better than men, but that they were often judged as having done a worst job than their male counterparts – at least when they were the first women on the job. In fact, the study found that by the time the second round of women leaders were elected, they were rated on par with men.

The lesson learned, yet again: first women are inherently judged under a harsher set of standards and face elevated scrutiny than their male peers. But through their service, these trailblazers inevitably shift cultural perceptions of women as leaders.

We’re seeing this now in the race for the presidency, particularly in the male-dominated field of national security.

MSNBC recently asked voters: “With the field of Democratic candidates reduced to two, who would make the best Commander in Chief of the United States Armed Forces?” Senator Hillary Clinton was the clear favorite, besting her male opponent 50% to 35%–a ratio surprised any number of journalists and, probably, quite a few voters who weren’t among the 50% who chose her.

We assume that women will have a hard time being seen as competent in the area of national security because it is traditionally regarded as a masculine domain. A Roper ASW poll conducted in 2000 showed that 70% of respondents believed that a male president would perform better on foreign policy than a female president would. At the time, a woman president outranked men only on the issues of trustworthiness and honesty.

Yet attitudes have been changing at lightening speed. By 2007, a similar Roper poll showed a dramatic change: more than half of Americans felt that women were either equally suited or better suited to handle the complex issues of foreign policy, homeland security and the economy than their male counterparts.

It’s a huge cultural shift, and one that owes its evolution to the mantra of “seeing is believing.” Americans have become familiar with women leading in the area of national security; they’ve had the benefit of a decade spent watching Madeleine Albright and Condoleezza Rice occupy the highest security positions in our country. Simply put, these women have made it “normal” to have women in those positions by way of their mere presence.

And it’s not just the highest ranking officials who matter. The nightly news from Iraq features women who, whether as enlisted soldiers or as officers, are serving on the front lines of war and in the line of fire. Meanwhile, Senator Clinton herself has served on the Senate Armed Forces Committee and, of course, has suffered for her vote that allowed Bush to go to war in Iraq. But beyond this, she has been able to speak with authority to voters about her plans for withdrawal and ending the war, as well as about the importance of diplomacy.

“No More Waiting: Women in Politics and In a Time of War” is the subject of the new afterward to my book, Closing the Leadership Gap. I chose to explore the issue of security because it is perhaps the most important challenge that we face as a nation and as a global community. Women’s leadership on this issue is paramount, and voters are realizing that women must take the lead to formulate new ways of envisioning and ensuring security. On the international level, we see this not only through the women-elected heads of state from Liberia to Chile, but through the increased attention to using more women in the field (as urged by the UN Security Council’s 2000 resolution). The European Parliament followed suit, advising its members to have women make up 40% of all reconciliation, peace-keeping, peace-enforcement, peace-building and conflict prevention posts.

As a woman candidate trained in security issues by The White House Project put it in her stump speech, “Let diplomacy be our pre-emptive strike.” As much as any other argument, her words capture the essence of what women can bring to our political process—and why the polls are showing increased support for women leaders on security issues worldwide. We are beyond the firsts for women to lead in this arena on the national stage. What we need now is a critical mass of women to permanently shift the conversation and the security paradigm under which we currently operate. And despite the media’s doubting, voters have confirmed that they are ready for a woman to lead us.