Russian threats to use nuclear weapons during the war in Ukraine are a sign of "weakness" and fail to spook NATO and other nearby countries, the head of the National Nuclear Security Administration said.Why it matters: A new nuclear paradigm is creeping in.The U.K. and France are debating the future of their arsenals and reach.Poland has urged the U.S. to send some weapons its way.And the New START arms control treaty lapsed months ago.Driving the news: Speaking at the Hudson Institute in Washington, NNSA boss Brandon Williams said Russian saber rattling signals a "lack of conviction and confidence in their conventional forces against a much, much, much, much, much smaller" Ukraine.The war, which has killed or injured more than 1 million people, is now in its fifth year.Threat level: Russia and the U.S. together wield some 85% of the world's nuclear warheads. China, meanwhile, is undertaking a historic expansion."Deterrence isn't quite the same as it was during the Cold War," Williams said. "But it does begin with our nuclear arsenal."The U.S. is overhauling every leg of its triad. The combined 2025-34 nuke plans of the Defense and Energy departments amount to $946 billion, the Congressional Budget Office said.Flashback: Russia and neighboring Belarus conducted nuclear drills in May.The former's defense ministry said they involved tens of thousands of troops, hundreds of launchers and aircraft and dozens of warships, including several ballistic missile submarines.Go deeper: China's nuke tests "are not small," NNSA boss says