Gianluca Busio and Walker Zimmerman highlight USMNT Olympic squad's June camp roster ahead of Paris Games

The U.S. Olympic team announced their June camp roster on Wednesday, with 25 players called in by Marko Mitrovic in the buildup to the Paris Games.

The U.S. have one friendly on the cards in June against Japan, and it will serve as the final warmup for the marquee event in France this July.

13 of the 21 players called in play abroad in Europe, while the remaining eight craft their trade domestically in MLS. Come Paris, Mitrovic will need to reduce his roster size to 18 participants.

GOALKEEPERS: Patrick Schulte (Columbus Crew), Gaga Slonina (Chelsea)

DEFENDERS: Nathan Harriel (Philadelphia Union), Jalen Neal (LA Galaxy), Bryan Reynolds (KVC Westerlo), John Tolkin (New York Red Bulls), Jonathan Tomkinson (Norwich City), Caleb Wiley (Atlanta United FC), Walker Zimmerman (Nashville SC)

MIDFIELDERS: Cole Bassett (Colorado Rapids), Gianluca Busio (Venezia), Benjamin Cremaschi (Inter Miami CF), Jack McGlynn (Philadelphia Union), Aidan Morris (Columbus Crew), Rokas Pukstas (Hajduk Split), Tanner Tessmann (Venezia)

FORWARDS: Paxten Aaronson (Eintracht Frankfurt), Esmir Bajraktarevic (New England Revolution), Taylor Booth (Utrecht), Cade Cowell (Guadalajara), Damion Downs (Köln), Johan Gomez (Eintracht Braunschweig), Duncan McGuire (Orlando City SC), Kevin Paredes (Wolfsburg), Griffin Yow (KVC Westerlo)

For the first time in the run-up to the Paris Games, Mitrovic called in an overage senior player to join the squad in Walker Zimmerman. The Nashville SC central defender, who has 41 senior national team caps, is expected to take one of three slots in July this summer.

In a press conference after announcing his June camp roster for a pair of pre-Copa America friendlies against Brazil and Colombia, first-team head coach Gregg Berhalter alluded to who some of those other overage players could be.

All three of Zimmerman, Auston Trusty and Brandon Vazquez were mentioned, while others like Alejandro Zendejas, Kellyn Acosta and Lennard Maloney have been touted as options, too.

The U.S. open the Paris Games on July 24 against Thierry Henry's France in Group A action. They'll then take on New Zealand and Guinea in tournament action to round out the Group Stage.

In the buildup to the Games, though, the U23 USMNT have an international friendly against Japan slated for June 11.