The White House is warning that Russia may seek to use chemical or biological weapons in Ukraine. But asked if such an move would cross a "red line" leading to U.S. military involvement, Jen Psaki says U.S. troops will not be sent to fight. (March 10) Subscribe for more Breaking News: http://smarturl.it/AssociatedPress Website: https://apnews.com Twitter: https://twitter.com/AP Facebook: https://facebook.com/APNews Instagram: https://www.instagram.com/APNews/ ​ You can license this story through AP Archive: http://www.aparchive.com/metadata/youtube/e57e431859b7461cad66eee45ca38ffc