Yes of course.
You will be able to assassinate other world leaders, plant spies in other countries, influence elections of other countries, (kinda like what people are alleging the Russians did in the 2016 U.S election) create agreements or allies with other countries, go to war with other countries… the possibilities are endless.
There are only a few countries you can really have interactions with (for example, no one cares if you go to war with Croatia, Andorra or Chile.
Only major countries like China, Russia, Brazil, Germany, U.K, Canada, Mexico etc will be featured prominently/ influence in some way.
If you go to war, and WIN, you can either rule the country you took over or place a “puppet” of yours to control it in your favor.
Just remember, going to war has many consequences! You could be assassinated, taken over by the opposing force, induce World War 3, or just have the wrath of the U.N on your back…