The U.S., Russia, Japan, China, India, et al. have all begun to develop the 5th-generation jet fighters long ago.

See http://en.wikipedia.org/wiki/Fifth_generation_jet_fighter#Aircraft .

Will that set a precedent for future arm races among the militarily powerful countries? After all, this world has become no less unstable.

One thing I've noticed in the above web link is that no country in South America has joined the race to develop 5th-gen jet fighters. That intrigues me.