Stuttgart-born goalkeeper David Yelldell plays in the German second division for Duisburg while Frankfurt native Timothy Chandler plays as a wing-back with Bundesliga club Nuremberg. Neither have represented the US at any level.
The squad features just four players from North America's Major League Soccer - New York Red Bulls pair Tim Ream and Juan Agudelo, Vancouver Whitecaps centre-half Jay DeMerit and Los Angeles Galaxy midfielder Landon Donovan.
The squad will begin training in North Carolina on March 20 before taking on Argentina on March 26 at the New Meadowlands stadium in New Jersey and then facing Paraguay at LP Field in Nashville, Tennessee.
Bradley's squad includes 16 members of the 2010 World Cup squad which reached the second round in South Africa before being eliminated by Ghana.
The US will compete in the CONCACAF Gold Cup in June where they have been drawn in a group with Canada, Panama and Guadeloupe.
"This is an important opportunity to get our core group together along with some relatively newer faces as we consider the roster decisions for the Gold Cup this summer," said Bradley.
"We have not had these players together for quite some time, so this is a great chance to get in a solid week of training and then face two quality opponents in Argentina and Paraguay."
Defenders: Carlos Bocanegra (Saint Etienne), Jonathan Bornstein (UANL Tigres), Timothy Chandler (Nürnberg), Steve Cherundolo (Hannover 96), Jay DeMerit (Vancouver Whitecaps), Oguchi Onyewu (Twente Enschede), Tim Ream (New York Red Bulls), Jonathan Spector (West Ham United), Zak Whitbread (Norwich City)
Midfielders: Michael Bradley (Aston Villa), Clint Dempsey (Fulham), Mikkel Diskeruud (Stabaek), Landon Donovan (Los Angeles Galaxy), Maurice Edu (Glasgow Rangers), Benny Feilhaber (Aarhus), Stuart Holden (Bolton Wanderers), Jermaine Jones (Blackburn Rovers), Sacha Kljestan (Anderlecht)
Forwards: Juan Agudelo (New York Red Bulls), Jozy Altidore (Bursaspor), Edson Buddle (Ingolstadt)