LAS VEGAS — The United States men’s national basketball team announced its Olympic roster Saturday night, filling the three spots it had remaining.


The Clippers’ Blake Griffin, the Thunder’s James Harden and the 76ers’ Andre Iguodala were added to the nine players who had already secured a spot. All three will play in their first Olympics.


The three players who were nominated but not selected to the roster were Rudy Gay, Eric Gordon and Anthony Davis, the top pick in this year’s N.B.A. draft.


Coach Mike Krzyzewski decided to place the biggest emphasis on athleticism. Many of the players who already had a spot on the team, like LeBron James, Kevin Durant and Kobe Bryant, can play guard or forward.


“This team has great versatility,” Krzyzewski said.


The team is full of players who have faced international competition, with 10 players who were on the 2008 Olympic or 2010 world championships teams, both events in which the United States took home a title.


“We have more playmakers in the second unit than in 2008,” Bryant said. “We have to try to take full advantage of those guys.”


The only major concern for the team is its lack of size. Part of that is because of injuries to LaMarcus Aldridge (labral tear in hip), Chris Bosh (strained abdominal muscle) and Dwight Howard (herniated disk).


Kevin Love, one of the few players taller than 6 feet 8 inches, said he would play center instead of his usual power forward position.


The team will be loaded with high-quality guards. Every guard besides Harden has appeared in an N.B.A. All-Star Game.


Jerry Colangelo, the United States basketball chairman and managing director, said he believed this team would be successful despite injuries to All-Star-caliber players.


“I think we’ve put together a terrific team with great athleticism,” Colangelo said. “We think we’re deeper than 2008, and I think we’re more talented.”


Even if Colangelo and this group win the gold medal, it may be hard to compare this team to the 2008 group.


The United States is again considered the gold medal favorite, and the 12 players understand that falling short of the title would be a national disappointment.


On Saturday, many of the players expressed how important it was to represent the country that in large part has shown the world how to play the sport at a high level. The 1992 Dream Team is thought to have spurred the expansion of basketball globally.


But eight years ago, in the 2004 Olympics, the United States settled for the bronze medal.


James, who was on that team, said he did not want anything less than gold.


All of James’s accomplishments are on display in his office at his home, including his Most Valuable Player trophies and his gold medal from 2008. His first N.B.A. championship ring will soon be there.


James said he did not display his bronze medal, though, and could not remember the last time he looked at it.


“That’s not an accomplishment,” James said.


All of the players know winning the gold is not a given, and will not be nearly as easy as it was for the 1992 team, which won by an average of 44 points.


Bryant says he expects that the United States players will have to do more preparation than in the N.B.A., where every team has solid knowledge of other players.


Bryant said he and his teammates would be seeing many opposing players in the Olympics for the first time.


“This is a big challenge for us,” Bryant said. “I feel like the rest of the world feels the gap is closing.”


Along with athleticism, the national team will be using younger players in London than in past Olympics; Durant, Griffin, Harden, Love and Russell Westbrook are 25 or younger.


Bryant, 33, now the oldest player in the group, says he is responsible for helping the younger players prepare for London — although he says he will not give too many secrets that have helped him become a five-time N.B.A. champion.


“Our youth brings speed and aggression and we love that,” Bryant said. “Kevin Durant and Kevin Love are amazing players. Coach Krzyzewski has the packages to where there are so many things with our team he can do.”


But it is no secret that the one expected to lead the way is James. He faced numerous challenges in his run to an N.B.A. title with the Miami Heat, including a Game 7 win over the Boston Celtics. James knows the mentality the United States team must take when it begins play in London.


“We have to approach every game,” James said, “like it’s Game 7.”