A U.S. intelligence agency has issued a strong warning that attacks on the November elections are underway.Leaders at the U.S. National Counterintelligence and Security Center issued warned Friday that current and ongoing threats and attacks are targeting American campaigns, candidates, citizens and elections. The warning also names names, calling out China, Russia and Iran.And it warns Americans that those and other adversaries are trying to manipulate them in a "direct threat to the fabric of our democracy."Earlier this week, the National Investigative Unit, citing a letter from senior congressional leaders, reported election attacks may already be underway. And the head of U.S. Cyber Command, Gen. Paul Nakasone, assured the public that, "When we see our adversaries attempting to interfere with democratic processes, we will act."The warning also urges Americans to check out sources of information before sharing or posting, use a critical eye and improve digital habits and media literacy.Shortly after the announcement, senior Democratic leaders in Congress pressed the director of National Intelligence to go further and release more specifics, saying the election security warning "does not go nearly far enough in arming the American people with the knowledge they need."Read the full alert here.Take a look at the video above for moreMark Albert is the chief national investigative correspondent for the Hearst Television National Investigative Unit, based in Washington D.C.Know of election security problems or voter suppression? Have a confidential tip? Send information and documents to the National Investigative Unit at investigate@hearst.com.