Norwich City defender Zak Whitbread, born in Texas but raised in Runcorn in North West England, has featured for the United States at Under-20 level but this is his first senior call-up.
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 U.S. 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.
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.
"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)
