creating a new column based on a set of strings conditions

I have this column with a lot of countries.

countries <- c(Germany, France, Japan, China, Angola, Nigeria)

I want to create a new column called continent, agreggating these places. For example, I tried this but it didn't work:

if (countries == "Germany" | "France" {
   countries$continents <- "Europe"
 } else if (countries == "Japan"  |"China") {
   countries$continents <- "Asia"
 } else if (countries == "Angola"  |"Nigeria") {
   countries$continents <- "África" 

But R keep saying me i'm not allowed to compare strings. Maybe dplyr might have a clever solution, but any solution is welcomed. How I do this?