US General Curtis Scaparrotti told lawmakers that Russia is working to break up the NATO alliance, partly through its online operations to spread false information.

"Russia is carrying out a campaign of destabilization to change the international order, fracture NATO and undermine US leadership around the world," Scaparrotti told the Senate Armed Services Committee, which provides civilian oversight to the military.

"Throughout Europe, along its periphery in the Middle East and beyond, Russia has demonstrated a willingness and capability to exert influence, spread disinformation and undermine confidence in NATO. ... At sea, on land, in the air -- frankly, every domain -- Russia's increasingly modernized military is operating at levels not seen since the Cold War."

Democratic Senator Jack Reed asked Scaparrotti if he thought there was a "unified effort" among all US government agencies to confront the Russian cyber threat.

"I don't believe there's an effective unification across the interagency, with the energy and the focus that we could attain," Scaparrotti said.

Russian influence spans Europe, Scaparrotti said, but the area that concerned him the most is the Balkans.

"Russia's at work in the Balkans, and I think that we've kind of taken our eye off the area," he said.

"It's an area where, in terms of diplomacy, we have to put some focus, in my opinion. And we have to continue our security reform and our capability building that we and the international community's engaged in the Balkans."