Jurgen Klinsmann has been fired as the manager of the United States men's national team, the U.S. Soccer Federation announced on Monday.

U.S. Soccer did not immediately name a replacement in a statement that thanked Klinsmann for his efforts, but sources told ESPN FC that negotiations are ongoing with LA Galaxy coach Bruce Arena to take over the job for a second time.

Klinsmann took charge of the U.S. men's squad in 2011 and led it into the knockout stage at the 2014 World Cup.

But disappointing results since then put his job in jeopardy, with defeats to Mexico and Costa Rica in World Cup qualifiers this month proving to be the last straw.

"We want to thank Jurgen for his hard work and commitment during these last five years," U.S. Soccer president Sunil Gulati said in a statement. "He took pride in having the responsibility of steering the program, and there were considerable achievements along the way.

"Many are aware of the historic victories, including leading us out of the Group of Death to the Round of 16 in the 2014 FIFA World Cup, but there were also lesser publicized efforts behind the scenes. He challenged everyone in the U.S. Soccer community to think about things in new ways, and thanks to his efforts we have grown as an organization and expect there will be benefits from his work for years to come."

Arena's contract with the Galaxy was set to expire next month, but the 65-year-old recently signed a two-year extension with the MLS club, multiple sources said. However, the new deal would allow Arena -- who coached the U.S. at the 2002 and 2006 World Cups -- to leave if he were offered the national team job.

Klinsmann had been under contract through the 2018 World Cup, but the U.S. lost 2-1 to chief rival Mexico in Columbus, Ohio, on Nov. 11, and then 4-0 away to Costa Rica four days later.

The results left the U.S. at the bottom of the six-team regional CONCACAF group with eight games to play. The top three teams qualify for the World Cup, while the fourth will enter a two-legged intercontinental playoff against a team from the Asian confederation for one of the final spots in Russia.

Jurgen Klinsmann was fired after his team lost to Mexico and Costa Rica this month. Joe Maiorana-USA TODAY Sports

In interviews on Sunday, Klinsmann said he was "1,000 percent" certain that the U.S. would still qualify, and then said he was "not afraid" at the prospect of losing his job, while also saying his critics "don't understand soccer or the team." He also discussed tactics in a Q&A with fans on Facebook, which made Monday's firing appear all the more sudden.

"While we remain confident that we have quality players to help us advance to Russia 2018, the form and growth of the team up to this point left us convinced that we need to go in a different direction," Gulati's statement continued. "With the next qualifying match in late March, we have several months to refocus the group and determine the best way forward to ensure a successful journey to qualify for our eighth-consecutive World Cup.

"There has never been a greater time for soccer in this country, and with the support and efforts of the millions of fans, sponsors, media and friends, we look forward to continued progress in the game we all love."

Klinsmann received praise for leading the U.S. through a difficult group at the 2014 World Cup, only to lose to Belgium in extra time in the round of 16.

U.S. Soccer has parted ways with #USMNT Head Coach and Technical Director Jurgen Klinsmann: https://t.co/iCc8DA5RGB - U.S. Soccer (@ussoccer) November 21, 2016

But since then, the U.S. finished a disappointing fourth at the 2015 CONCACAF Gold Cup, then in October of last year lost a Confederations Cup playoff to Mexico in a game that was seen as key for preparing for 2018.

The World Cup qualifying campaign was not without incident in the previous round, as Klinsmann's men lost 2-0 at Guatemala in March.

Klinsmann's job was thought to be in jeopardy during the Copa America tournament in June, but the U.S. reached the semifinals. However, the gulf between the Americans and the world's elite nations was clear in their 4-0 defeat to Argentina.

A former star player for Germany, Klinsmann spent the end of last week in his homeland, where he attended a state dinner with German chancellor Angela Merkel and U.S. president Barack Obama, who the coach said was supportive following the recent defeats.

"He said, 'Coach, it didn't go well in Costa Rica, but it's only the start of the World Cup qualifying and you'll get back on the right track,'" Klinsmann said of his conversation with Obama. "He understands that it's a long qualifying process. He also understands dynamics of soccer as a global sport and how it builds bridges."

ESPN FC's United States reporter Jeff Carlisle contributed to this report.