What are the names of countries that have both players with position forward and players with position defender?
SELECT T1.Country_name FROM country AS T1 JOIN match_season AS T2 ON T1.Country_id  =  T2.Country WHERE T2.Position  =  "Forward" INTERSECT SELECT T1.Country_name FROM country AS T1 JOIN match_season AS T2 ON T1.Country_id  =  T2.Country WHERE T2.Position  =  "Defender"
SELECT T1.Country_name FROM country AS T1 JOIN match_season AS T2 ON T1.Country_id  =  T2.Country WHERE T2.Position  =  "Forward" INTERSECT SELECT T1.Country_name FROM country AS T1 JOIN match_season AS T2 ON T1.Country_id  =  T2.Country WHERE T2.Position  =  "Defender"
[{'Country_name': 'United States'}]