General Joseph Dunford, slated to be the next Chairman of the Joint Chiefs of Staff, spoke to the Senate Armed Services committee during his confirmation hearing. “Russia presents the greatest threat to our national security. If you want to talk about a nation that could pose an existential threat to the United States, I would have to point to Russia. And if you look at their behavior, it’s nothing short of alarming.”
According to CNN, the reasons that Russia poses such a threat are the country’s role in the Ukraine, the threat it poses to NATO nations that surround it, and its massive nuclear weapons cache.
Dunford feels that the U.S. should help the Ukrainian government by providing anti-tank and artillery assistance in response to the current standoff with Russia. “Frankly, without that kind of support, they’re not going to be able to protect themselves against Russian aggression,” he said.

State Department spokesman Mark Toner said Secretary of State John Kerry “doesn’t agree with the assessment that Russia is an existential threat to the United States, nor China, quite frankly.”
Kerry spoke about Iran as “the most destabilizing element in the region and clearly a malign influence.” He also pointed out Tehran’s support for the Houthi rebels in Yemen and Hezbollah in Lebanon, and its participation in Syria and Iraq. “They’re creating, I think — they’re exacerbating, at least — the Sunni-Shia sectarianism across the region,” he said.