How to search by country with twtteR

I'm trying to gather tweets from specific countries, I've been using the following code to search for tweets in a radius around a geo code. And then storing them in a csv file for mapping.

tweets <- searchTwitter("", n = 5000, geocode='53.412910,-8.243890,100mi')

In wondering if there is an easier way to search for tweets from specific countries? Also is there a way to search for tweets with geo location turned on? Should I use a different package like Rtweet?

Thanks for the your time and help.