Older, shorter, female or even foreign — U.S. allies in Asia are looking beyond their traditional military recruitment profile to secure enough troops and handle the growing security challenges posed by China and North Korea.

Japan and the Philippines each have simmering territorial disputes with China, while a wider swath of countries, including Australia and South Korea, shares concerns about the economic devastation that could be wrought if they lose access to key sea lanes.

For all of them, Russia’s war on Ukraine has served as a reminder that an alliance with the U.S. may not be enough to thwart possible attacks. In particular, it’s highlighted the sheer number of boots on the ground, not just equipment, needed in the event of such aggression. Yet some Asian countries, most notably Japan, face a shrinking pool of young recruits even as they fret over a possible contingency involving the huge armies boasted by some of their neighbors.