The US Director of National Intelligence says that Russia and other foreign entities are '"likely" to pursue more cyber attacks on American and European elections in an attempt to undermine democracy in coming elections, including the 2018 midterms.

"Persistent and disruptive cyber operations will continue against the United States and our European allies using elections as opportunities to undermine democracy," Dan Coats said Tuesday during an annual Senate Intelligence Committee hearing on threats.

"Frankly, the United States is under attack," Mr Coats said.

Mr Coats said that Russia is the biggest threat, alongside the likes of China, Iran, and North Korea in terms of cyber threats. Terrorist, criminal organisations, and even individuals could also pose a cyber threat.