avoid USA using here.com with Rstudio

Question

I'm trying to get some routes with here.com using Rstudio for Canada, from side to side but making sure I exclude getting in the US. I've found exclude in Routing but I can't find a way to allocate it in route() function, or don't know where to include. Also used avoid_area = USA as shown in their guide through this link using US shapefile as criteria for the function, where I named the shp USA and that's what I added in the function as specified below, and no luck because it's returning fewer options than if I didn't include that piece, how do I exclude USA for Canadian routing using here.com?

# Packages
library("sf")
library("tidyverse")
library( "hereR")
library("stringi") 
library("dplyr")

# Load data
address <- structure(list(Origin = "Fredericton", Lat1 = 45.9379251883697, 
    Lon1 = -66.593737477555, Destination = "Richmomnd", Lat2 = 45.8767690820575, 
    Lon2 = -66.3300656050966), row.names = c(NA, -1L), class = c("tbl_df", 
"tbl", "data.frame"))
# Set API key for free through throug https://developer.here.com/self-serve
set_key(api_key = "YOUR_FREEMIUN_KEY") 

# Create SFDFs  (points with lat-lon pairs):
dist.pairs.input.1 <- dist.pairs.query %>%  
  st_as_sf(coords = c("Lon1","Lat1"), 
           crs = "WGS84", 
           remove = F)
dist.pairs.input.2 <- dist.pairs.query %>% 
  st_as_sf(coords = c("Lon2", "Lat2"), 
           crs = "WGS84", 
           remove = F)

# Get routing:
query_result <- route(origin = dist.pairs.input.1, 
                      destination = dist.pairs.input.2,
                      traffic = T,
                      avoid_area = USA) # where USA is USA's shapefile