Come January, women will head three of the six largest US weapons makers, a sign that their clout in the male-dominated industry is growing.
But executives and experts say the trend may be short-lived unless more young women choose engineering careers and defense companies figure out how to keep them.
Marillyn Hewson and Phebe Novakovic move into the CEO offices at Lockheed Martin Corp and General Dynamics Corp respectively on Jan. 1, joining trailblazer Linda Hudson, who became the first woman to head a major U.S. defense firm in 2009 when she was named CEO of BAE Systems Plc's U.S unit.
The promotions put them in a small club of 19 female CEOs who head Xerox, Hewlett Packard and other Fortune 500 companies.
But Hudson, 62, said Hewson and Novakovic's new jobs shouldn't be taken as signals that defense companies are now paradigms of equal opportunity for women.
I will be more convinced the industry has made a dramatic shift when I see significant numbers of female executive leaders at all levels of management throughout the entire industry, Hudson said.
Women have been making slow but steady inroads in science, technology, engineering and math (STEM) fields, and accounted for 14 percent of working engineers in 2009, up from 1 percent in 1960, the Association of American University Women said.
And women are gaining more promotions in the second-tier of management at defense companies. Boeing Co this month appointed five women to senior posts, two heading reorganized defense divisions.
But the wave of female engineers and scientists entering the defense business has stalled or reversed. In 2010, women earned 18.4 percent of U.S. bachelor engineering degrees, down from a peak of nearly 21 percent in 2002 and unchanged from the 1980s, according to the National Science Foundation.
In computer science, women earned only 18.2 percent of degrees in 2010, down from nearly 28 percent a decade ago.
You're seeing women move up within corporations. You're seeing a lot more mentoring inside companies, said Karen Panetta, who teaches engineering at Tufts University and edits Women in Engineering magazine.
But the number of women going into technical engineering fields is a real problem.