And by strongest, i mean by military power, economic power/growth, influence, education, health, technology, etc.
this is a serious topic. don't post a country just because it's YOUR country, give a legitimate reason why.
my vote is Russia
i say this because of it's massive influence throughout history. For example, at one point literally all of eastern europe was either annexed into the Soviet Union or a soviet satellite state, excluding Greece. It takes a lot of military strength and ideological power to force THAT many countries into your alliance.
something the USA could never do.