I am trying to create a world map highlighting the top terrorist activities. turns out that the output doesnot include the map zone for US

I am trying to plot top attack zones as per countries but I am not being able to get all countries in my map. for example USA and the united kingdom. Can anyone assist me with this? the map pic is included below

df4 %>% 
  ggplot(aes(fill = n, map_id = country)) +
  geom_map(map = world_map)+ 
  expand_limits(x = df4$longitude, y = df4$latitude) +
  coord_map()+
  
  
  theme_map()+
  #scale_fill_distiller(palette = "YlGnBu", direction = 1)+
  scale_fill_gradient(low = "grey", high = "red", name = "No. of attacks") +
  #geom_polygon(aes(longitude, latitude), fill = NA, colour = "grey60")
  
  #geom_text(data = df4, aes(longitude, latitude, label = country, group = NULL), size = 2.5)+
  ggrepel::geom_label_repel(data = df4, 
                            aes(longitude, latitude), 
                            label = df4$country,
                            size = 2.5,
                            col = "black")+
  #big leg
  guides(fill = guide_colourbar(barwidth = 0.5,
                                barheight = 20))+
  theme(legend.position="right",
  )+
  theme(legend.title = element_text(color = "Black", size = 10, face = "bold"))