Mexico.
cuba
Mexico
Mexico and Canada both share borders with the US.
Greenland
Canada and Mexico share land borders with the United States, making them the closest countries to the United States. The closest country to the US with which the US does not share a border is Russia, at the Bering Strait.
Other than Canada and Mexico, the closest country to the United States is Russia. The eastern tip of Russia, Big Diomede Island, is less than 4 km from the western tip of Alaska, Little Diomede Island.
The correct answer would be the United States of America; but if you mean what foreign country, that would be Mexico.
Canada and Mexico are foreign countries that border the U.S.A. Canada is to the north and Mexico is to the south.
mexico
Mexico- but Canada is south of a large part of the US called Alaska!
Mexico, to the south.