The US-China rivalry is "significant," and "we do have to make sure that we don't stumble into conflict," warned Condoleezza Rice, who served as national security adviser and Secretary of State under former President George W. Bush. "We have to recognize that this is a rivalry militarily, economically, and a rivalry in terms of technology," Rice told Yahoo Finance at the KPMG Women’s Leadership Summit on Wednesday (video above). "We can't sweep that under the rug." Former U.S. Secretary of State Condoleezza Rice testify's during a Senate Judiciary Committee confirmation hearing for U.S. Supreme Court nominee judge Brett Kavanaugh on…