Team USA Olympians -- We're NOT Scared About Terror Attacks ... But Fans Should Be

With the U.S. and Russian military on high alert for terror attacks at the Winter Olympics in Sochi, two U.S. athletes tell TMZ Sports they're NOT worried about their own safety ... but they ARE concerned about the fans.

There have been several reports that Russian officials are on the hunt for two female "black widow" suspects, who are planning to carry out suicide attacks during the games.

But Team USA bobsledder Cory Butner (above left) and curling star Jeff Isaacson (above right) say they're confident Olympic security will keep the athletes "100% safe."

"I feel 100% safe as an athlete," Isaacson says ... "[Olympic Village] is going to be the safest place in the world."

But he acknowledges, "I'd be extra cautious if I was a spectator."

Butner echoed Isaacson's sentiments ... "I feel confident in our safety as athlete ... I do have concerns for my family coming to watch. I just pray that they are safe"

Despite the concern, Butner says his family told him to focus on his race and "not worry."