LAS VEGAS -- Gregg Popovich on Sunday night gathered his newly-formed Team USA for its first in the six-week journey toward the World Cup in China.

He'd been preparing for this gathering in one way or another for almost four years, since he was named as Mike Krzyzewski's successor in late 2015. The message he delivered to the patchwork roster was aimed at responsibility and unity, two things he thinks are going to be vital. Not just because Team USA has had numerous players drop out of this summer's event but also because of the weight of playing with "USA" on their chests at this point in time.

"It's our responsibility to not only be the best team we can be but also conduct ourselves with the USA on our shirt, we're representing a lot of people," Popovich said after he conducted his first training camp practice Monday at UNLV. "We have a huge responsibility not only for the country to do this in a classy manner but to continue the success that USA basketball has had over the last 12 years."

Both Popovich and Team USA assistant coach Steve Kerr, who are known for making political statements, refrained from doing so Monday as they attempted to set a tone of unity.

"We can't fix the divisiveness in our country, but what we can do is be a great example of how people come together for a common goal and achieve it," Popovich said.

"I watched the women's World Cup team win the World Cup and it was inspiring," Kerr said. "To me that's what sports are about, the competition and the unity. Bringing out this great spirit and energy with the fans. We have a chance to do something that is very positive and unifying."

Popovich's roster was in flux up until this past weekend, with players still dropping out and being added. On Monday he made more roster changes as he promoted De'Aaron Fox and Joe Harris from the Select Team to play with the national team in practice. Fox ran point guard for the second unit backing up Kemba Walker as Kyle Lowry remained in a cast recovering from thumb surgery. Donovan Mitchell also played some point guard in the team's scrimmage.

More than a dozen players who were on the national team roster elected to remove their names, leaving the team thinner than is preferred at some spots.

"All I care about is who's here," Popovich said. "I've got a fine group of guys and we're going to get the best possible team we can...this is the most satisfying form of putting a bunch of guys together and them have empathy and love for each other to form the kind of team they're going to have to have to beat some really good European teams."

Popovich has poured himself into preparation for this job, studying everything from Team USA's history against certain opponents to opposing personnel with challengers from Europe to where in Shanghai he can get good wine.

"We're all used to pressure and those things but I can say a day hasn't gone by in the last year when I haven't thought about USA Basketball, what I would want to do with players, who are the coaches, it's been on my mind," Popovich said. "It's like thinking about two teams at the same time for that period. Coach K did that for 12 years so I can try to do the same."