I think that Volare by Domenico Modugno is the only song originally issued in Italy to top the American Singles Charts. It sold over a million copies in Italy alone.
The song proved so popular that Dean Martin, Jesse Belvin, and Nelson Riddle all issued singles but none could beat Modugno’s as it topped the Billboard Hot 100 and Best Sellers In Store Chart for five weeks beginning August 18, 1958.
His other claim to fame was playing the part of Athos in the American television series The Three Musketeers. He never had another top 50 single in the United States.