Some airlines are planning to add fees for the first checked bag on transatlantic flights. While fees for checked bags have quickly become standard on domestic flights, international routes have so far have been spared. But travelers should expect that to change. The fee goes hand in hand with the expansion of basic economy tickets, which don't include any “extras” — like seat assignments.

http://www.travelandleisure.com/airlines-airports/delta/delta-airlines-checked-bag-fee-transatlantic-flights