(Reuters) - United States coach Juergen Klinsmann says he will now turn to youth after his team's World Cup ended in a second-round defeat by Belgium.

The U.S. lost 2-1 in extra-time on Tuesday and although Klinsmann praised the effort and spirit of his team during the tournament his thoughts have quickly turned to refreshing the squad with new faces.

"This transition year coming up is definitely the opportunity to bring a lot of young players through the ranks and see what they are capable to do," the German told a farewell news conference at the team's base on Wednesday.

Klinsmann said he would be discussing with age-group coaches the likely contenders to move up from the youth squads into the full team.

The U.S. World Cup squad featuring several players who will be in the mid-thirties in four years time.

Forward Clint Dempsey, midfielders Kyle Beckerman and Jermaine Jones and full back DaMarcus Beasley are all in their thirties but Klinsmann said that while he wanted to see new faces it would not be a case of swiftly abandoning older players.

"There is no 'thank you and bye' it is always defined by performance what you bring to the table," he said.

"I think a good thing about going into the next year is that we have the opportunity to see a lot of young players, coming into our platform in the senior team. We can give them the time to show where they are at right now.

"The experienced players, or older players, we can tell them now for the next couple of months, play in your club environment. We know you inside-out anyway, we know what you bring to the table," Klinsmann added.

"Maybe there is the time now with the next couple of friendlies that are coming up and over the next year, (to) see the young players grow and see how far they can make it," he said.

NEW OPTIONS

The former Germany striker and coach said he wanted to learn what realistic new options he had available before next June's CONCACAF Gold Cup and that would be the moment of truth for the older generation.

"Obviously there is the Gold Cup where want to go with the strongest team possible and see how many of the more experienced players are still in it or how many of them are out," he said.

Klinsmann was again critical of his team's failure to take the game to opponents, saying they sometimes showed too much respect and that this mental approach had to change.

"We have to start implementing all those elements with our Under-17, Under-18, Under-20 and the Under-21 team which will be our Olympic team. That is the next generation that is going to come in - the more we get the message to those kids, the more we will benefit in a couple of years from now," he said.

Although upbeat about the booming interest in soccer in the States, Klinsmann said the national team was essential to developing the sport in the country and that there remained plenty of room for improvement.

"When you go out in the round of 16, clearly it gives you the message that you have a lot of work still ahead of you," he said.