Joseph Dunford
Marine Corps General Joseph Dunford testified during the Senate Armed Services committee nomination hearing to be chairman of the Joint Chiefs of Staff on Capitol Hill in Washington, D.C., July 9, 2015. Reuters

Russia provides a greater threat to the United States’ existence than any other foreign nation, Joint Chiefs of Staff Chairman nominee Gen. Joseph F. Dunford told a Senate subcommittee Thursday. Dunford added that the United States should consider arming Ukraine to combat “Russian aggression” in the eastern Ukraine conflict, which has killed more than 6,400 people since it began early last year.

Speaking to the Senate Armed Services Committee, Dunford pointed to Russia’s nuclear arsenal and recent increase in military activity in Eastern Europe as evidence to the threat it could pose, the Washington Post reported. The United States, as well as the European Union and NATO, have repeatedly accused Russia of providing weapons and even troops to support pro-Russian separatist rebels active in eastern Ukraine.

“If you want to talk about a nation that could pose an existential threat to the United States, I’d have to point to Russia,” Dunford said, according to the Washington Post. “If you look at their behavior it’s nothing short of alarming.”

Ukrainian government forces and separatist rebels signed a ceasefire deal in February that called for both sides to remove heavy weaponry, such as artillery, from the conflict’s frontlines. But the two sides have engaged in scattered skirmishes for months in violation of the truce. The United States has yet to provide lethal weaponry to Ukraine to aid in its fight, despite support for the idea from Defense Secretary Ash Carter and outgoing Joint Chiefs Chairman Gen. Martin Dempsey, CNN reported.

Asked for his opinion on the matter, Dunford said Ukraine would need U.S. weaponry to stave off Russian military activity in the region.

“Chairman, from a military perspective I think it’s reasonable that we provide that support to the Ukrainians,” Dunford told Sen. John McCain (R.-Ariz.), chairman of the Senate Armed Services Committee. “And frankly, without that kind of support, then they’re not going to be able to protect themselves against Russian aggression.”

The Kremlin has repeatedly denied any direct involvement in the eastern Ukraine conflict. Russian President Vladimir Putin said any Russian nations active in eastern Ukraine were volunteers acting of their own accord, the BBC reported.