In a broad sense this is inaccurate - war has been around as long as humans, and yet we were on an exponential population growth curve until the demographic transitions started.

Over the last century we as a species have significantly reduced child mortality, improved education, infrastructure, overall quality of life, and established reproductive health initiatives that supply condoms and sex education!

These advancements cause the local mortality rate to plummet. Then the following generation gets to reproductive age but has much less offspring, and the reproductive rate falls farther than the mortality rate did.

This is called the "demographic transition" and has occurred across dramatically different cultures, environments, and economies.

This is not universal or inevitable across the globe but the impact is so significant that global population as a whole is currently heading towards a plateau!

Therefore condoms, reproductive healthcare, and distributed economic growth are more effective at reducing population growth than bombs and bullets.

Developing a nation is literally more cost-efficient than destroying it. For the species. Not for the people selling the bombs.